511 lines
16 KiB
C
511 lines
16 KiB
C
/*
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* Xen 9p backend
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*
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* Copyright Aporeto 2017
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*
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* Authors:
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* Stefano Stabellini <stefano@aporeto.com>
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*
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*/
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/*
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* Not so fast! You might want to read the 9p developer docs first:
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* https://wiki.qemu.org/Documentation/9p
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*/
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#include "qemu/osdep.h"
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#include "hw/9pfs/9p.h"
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#include "hw/xen/xen-legacy-backend.h"
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#include "hw/9pfs/xen-9pfs.h"
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#include "qapi/error.h"
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#include "qemu/config-file.h"
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#include "qemu/main-loop.h"
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#include "qemu/option.h"
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#include "fsdev/qemu-fsdev.h"
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#define VERSIONS "1"
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#define MAX_RINGS 8
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#define MAX_RING_ORDER 9
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typedef struct Xen9pfsRing {
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struct Xen9pfsDev *priv;
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int ref;
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xenevtchn_handle *evtchndev;
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int evtchn;
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int local_port;
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int ring_order;
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struct xen_9pfs_data_intf *intf;
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unsigned char *data;
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struct xen_9pfs_data ring;
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struct iovec *sg;
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QEMUBH *bh;
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Coroutine *co;
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/* local copies, so that we can read/write PDU data directly from
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* the ring */
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RING_IDX out_cons, out_size, in_cons;
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bool inprogress;
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} Xen9pfsRing;
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typedef struct Xen9pfsDev {
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struct XenLegacyDevice xendev; /* must be first */
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V9fsState state;
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char *path;
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char *security_model;
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char *tag;
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char *id;
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int num_rings;
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Xen9pfsRing *rings;
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} Xen9pfsDev;
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static void xen_9pfs_disconnect(struct XenLegacyDevice *xendev);
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static void xen_9pfs_in_sg(Xen9pfsRing *ring,
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struct iovec *in_sg,
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int *num,
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uint32_t idx,
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uint32_t size)
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{
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RING_IDX cons, prod, masked_prod, masked_cons;
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cons = ring->intf->in_cons;
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prod = ring->intf->in_prod;
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xen_rmb();
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masked_prod = xen_9pfs_mask(prod, XEN_FLEX_RING_SIZE(ring->ring_order));
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masked_cons = xen_9pfs_mask(cons, XEN_FLEX_RING_SIZE(ring->ring_order));
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if (masked_prod < masked_cons) {
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in_sg[0].iov_base = ring->ring.in + masked_prod;
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in_sg[0].iov_len = masked_cons - masked_prod;
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*num = 1;
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} else {
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in_sg[0].iov_base = ring->ring.in + masked_prod;
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in_sg[0].iov_len = XEN_FLEX_RING_SIZE(ring->ring_order) - masked_prod;
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in_sg[1].iov_base = ring->ring.in;
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in_sg[1].iov_len = masked_cons;
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*num = 2;
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}
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}
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static void xen_9pfs_out_sg(Xen9pfsRing *ring,
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struct iovec *out_sg,
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int *num,
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uint32_t idx)
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{
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RING_IDX cons, prod, masked_prod, masked_cons;
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cons = ring->intf->out_cons;
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prod = ring->intf->out_prod;
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xen_rmb();
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masked_prod = xen_9pfs_mask(prod, XEN_FLEX_RING_SIZE(ring->ring_order));
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masked_cons = xen_9pfs_mask(cons, XEN_FLEX_RING_SIZE(ring->ring_order));
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if (masked_cons < masked_prod) {
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out_sg[0].iov_base = ring->ring.out + masked_cons;
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out_sg[0].iov_len = ring->out_size;
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*num = 1;
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} else {
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if (ring->out_size >
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(XEN_FLEX_RING_SIZE(ring->ring_order) - masked_cons)) {
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out_sg[0].iov_base = ring->ring.out + masked_cons;
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out_sg[0].iov_len = XEN_FLEX_RING_SIZE(ring->ring_order) -
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masked_cons;
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out_sg[1].iov_base = ring->ring.out;
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out_sg[1].iov_len = ring->out_size -
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(XEN_FLEX_RING_SIZE(ring->ring_order) -
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masked_cons);
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*num = 2;
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} else {
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out_sg[0].iov_base = ring->ring.out + masked_cons;
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out_sg[0].iov_len = ring->out_size;
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*num = 1;
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}
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}
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}
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static ssize_t xen_9pfs_pdu_vmarshal(V9fsPDU *pdu,
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size_t offset,
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const char *fmt,
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va_list ap)
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{
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Xen9pfsDev *xen_9pfs = container_of(pdu->s, Xen9pfsDev, state);
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struct iovec in_sg[2];
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int num;
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ssize_t ret;
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xen_9pfs_in_sg(&xen_9pfs->rings[pdu->tag % xen_9pfs->num_rings],
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in_sg, &num, pdu->idx, ROUND_UP(offset + 128, 512));
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ret = v9fs_iov_vmarshal(in_sg, num, offset, 0, fmt, ap);
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if (ret < 0) {
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xen_pv_printf(&xen_9pfs->xendev, 0,
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"Failed to encode VirtFS reply type %d\n",
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pdu->id + 1);
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xen_be_set_state(&xen_9pfs->xendev, XenbusStateClosing);
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xen_9pfs_disconnect(&xen_9pfs->xendev);
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}
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return ret;
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}
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static ssize_t xen_9pfs_pdu_vunmarshal(V9fsPDU *pdu,
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size_t offset,
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const char *fmt,
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va_list ap)
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{
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Xen9pfsDev *xen_9pfs = container_of(pdu->s, Xen9pfsDev, state);
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struct iovec out_sg[2];
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int num;
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ssize_t ret;
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xen_9pfs_out_sg(&xen_9pfs->rings[pdu->tag % xen_9pfs->num_rings],
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out_sg, &num, pdu->idx);
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ret = v9fs_iov_vunmarshal(out_sg, num, offset, 0, fmt, ap);
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if (ret < 0) {
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xen_pv_printf(&xen_9pfs->xendev, 0,
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"Failed to decode VirtFS request type %d\n", pdu->id);
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xen_be_set_state(&xen_9pfs->xendev, XenbusStateClosing);
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xen_9pfs_disconnect(&xen_9pfs->xendev);
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}
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return ret;
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}
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static void xen_9pfs_init_out_iov_from_pdu(V9fsPDU *pdu,
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struct iovec **piov,
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unsigned int *pniov,
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size_t size)
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{
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Xen9pfsDev *xen_9pfs = container_of(pdu->s, Xen9pfsDev, state);
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Xen9pfsRing *ring = &xen_9pfs->rings[pdu->tag % xen_9pfs->num_rings];
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int num;
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g_free(ring->sg);
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ring->sg = g_new0(struct iovec, 2);
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xen_9pfs_out_sg(ring, ring->sg, &num, pdu->idx);
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*piov = ring->sg;
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*pniov = num;
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}
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static void xen_9pfs_init_in_iov_from_pdu(V9fsPDU *pdu,
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struct iovec **piov,
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unsigned int *pniov,
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size_t size)
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{
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Xen9pfsDev *xen_9pfs = container_of(pdu->s, Xen9pfsDev, state);
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Xen9pfsRing *ring = &xen_9pfs->rings[pdu->tag % xen_9pfs->num_rings];
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int num;
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size_t buf_size;
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g_free(ring->sg);
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ring->sg = g_new0(struct iovec, 2);
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ring->co = qemu_coroutine_self();
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/* make sure other threads see ring->co changes before continuing */
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smp_wmb();
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again:
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xen_9pfs_in_sg(ring, ring->sg, &num, pdu->idx, size);
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buf_size = iov_size(ring->sg, num);
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if (buf_size < size) {
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qemu_coroutine_yield();
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goto again;
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}
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ring->co = NULL;
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/* make sure other threads see ring->co changes before continuing */
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smp_wmb();
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*piov = ring->sg;
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*pniov = num;
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}
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static void xen_9pfs_push_and_notify(V9fsPDU *pdu)
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{
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RING_IDX prod;
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Xen9pfsDev *priv = container_of(pdu->s, Xen9pfsDev, state);
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Xen9pfsRing *ring = &priv->rings[pdu->tag % priv->num_rings];
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g_free(ring->sg);
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ring->sg = NULL;
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ring->intf->out_cons = ring->out_cons;
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xen_wmb();
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prod = ring->intf->in_prod;
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xen_rmb();
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ring->intf->in_prod = prod + pdu->size;
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xen_wmb();
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ring->inprogress = false;
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xenevtchn_notify(ring->evtchndev, ring->local_port);
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qemu_bh_schedule(ring->bh);
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}
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static const V9fsTransport xen_9p_transport = {
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.pdu_vmarshal = xen_9pfs_pdu_vmarshal,
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.pdu_vunmarshal = xen_9pfs_pdu_vunmarshal,
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.init_in_iov_from_pdu = xen_9pfs_init_in_iov_from_pdu,
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.init_out_iov_from_pdu = xen_9pfs_init_out_iov_from_pdu,
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.push_and_notify = xen_9pfs_push_and_notify,
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};
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static int xen_9pfs_init(struct XenLegacyDevice *xendev)
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{
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return 0;
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}
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static int xen_9pfs_receive(Xen9pfsRing *ring)
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{
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P9MsgHeader h;
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RING_IDX cons, prod, masked_prod, masked_cons, queued;
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V9fsPDU *pdu;
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if (ring->inprogress) {
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return 0;
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}
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cons = ring->intf->out_cons;
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prod = ring->intf->out_prod;
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xen_rmb();
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queued = xen_9pfs_queued(prod, cons, XEN_FLEX_RING_SIZE(ring->ring_order));
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if (queued < sizeof(h)) {
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return 0;
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}
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ring->inprogress = true;
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masked_prod = xen_9pfs_mask(prod, XEN_FLEX_RING_SIZE(ring->ring_order));
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masked_cons = xen_9pfs_mask(cons, XEN_FLEX_RING_SIZE(ring->ring_order));
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xen_9pfs_read_packet((uint8_t *) &h, ring->ring.out, sizeof(h),
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masked_prod, &masked_cons,
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XEN_FLEX_RING_SIZE(ring->ring_order));
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if (queued < le32_to_cpu(h.size_le)) {
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return 0;
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}
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/* cannot fail, because we only handle one request per ring at a time */
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pdu = pdu_alloc(&ring->priv->state);
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ring->out_size = le32_to_cpu(h.size_le);
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ring->out_cons = cons + le32_to_cpu(h.size_le);
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pdu_submit(pdu, &h);
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return 0;
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}
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static void xen_9pfs_bh(void *opaque)
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{
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Xen9pfsRing *ring = opaque;
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bool wait;
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again:
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wait = ring->co != NULL && qemu_coroutine_entered(ring->co);
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/* paired with the smb_wmb barriers in xen_9pfs_init_in_iov_from_pdu */
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smp_rmb();
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if (wait) {
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cpu_relax();
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goto again;
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}
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if (ring->co != NULL) {
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qemu_coroutine_enter_if_inactive(ring->co);
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}
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xen_9pfs_receive(ring);
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}
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static void xen_9pfs_evtchn_event(void *opaque)
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{
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Xen9pfsRing *ring = opaque;
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evtchn_port_t port;
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port = xenevtchn_pending(ring->evtchndev);
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xenevtchn_unmask(ring->evtchndev, port);
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qemu_bh_schedule(ring->bh);
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}
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static void xen_9pfs_disconnect(struct XenLegacyDevice *xendev)
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{
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Xen9pfsDev *xen_9pdev = container_of(xendev, Xen9pfsDev, xendev);
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int i;
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for (i = 0; i < xen_9pdev->num_rings; i++) {
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if (xen_9pdev->rings[i].evtchndev != NULL) {
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qemu_set_fd_handler(xenevtchn_fd(xen_9pdev->rings[i].evtchndev),
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NULL, NULL, NULL);
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xenevtchn_unbind(xen_9pdev->rings[i].evtchndev,
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xen_9pdev->rings[i].local_port);
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xen_9pdev->rings[i].evtchndev = NULL;
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}
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}
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}
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static int xen_9pfs_free(struct XenLegacyDevice *xendev)
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{
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Xen9pfsDev *xen_9pdev = container_of(xendev, Xen9pfsDev, xendev);
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int i;
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if (xen_9pdev->rings[0].evtchndev != NULL) {
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xen_9pfs_disconnect(xendev);
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}
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for (i = 0; i < xen_9pdev->num_rings; i++) {
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if (xen_9pdev->rings[i].data != NULL) {
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xen_be_unmap_grant_refs(&xen_9pdev->xendev,
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xen_9pdev->rings[i].data,
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(1 << xen_9pdev->rings[i].ring_order));
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}
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if (xen_9pdev->rings[i].intf != NULL) {
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xen_be_unmap_grant_refs(&xen_9pdev->xendev,
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xen_9pdev->rings[i].intf,
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1);
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}
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if (xen_9pdev->rings[i].bh != NULL) {
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qemu_bh_delete(xen_9pdev->rings[i].bh);
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}
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}
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g_free(xen_9pdev->id);
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g_free(xen_9pdev->tag);
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g_free(xen_9pdev->path);
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g_free(xen_9pdev->security_model);
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g_free(xen_9pdev->rings);
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return 0;
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}
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static int xen_9pfs_connect(struct XenLegacyDevice *xendev)
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{
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Error *err = NULL;
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int i;
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Xen9pfsDev *xen_9pdev = container_of(xendev, Xen9pfsDev, xendev);
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V9fsState *s = &xen_9pdev->state;
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QemuOpts *fsdev;
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if (xenstore_read_fe_int(&xen_9pdev->xendev, "num-rings",
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&xen_9pdev->num_rings) == -1 ||
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xen_9pdev->num_rings > MAX_RINGS || xen_9pdev->num_rings < 1) {
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return -1;
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}
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xen_9pdev->rings = g_new0(Xen9pfsRing, xen_9pdev->num_rings);
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for (i = 0; i < xen_9pdev->num_rings; i++) {
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char *str;
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int ring_order;
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xen_9pdev->rings[i].priv = xen_9pdev;
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xen_9pdev->rings[i].evtchn = -1;
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xen_9pdev->rings[i].local_port = -1;
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str = g_strdup_printf("ring-ref%u", i);
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if (xenstore_read_fe_int(&xen_9pdev->xendev, str,
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&xen_9pdev->rings[i].ref) == -1) {
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g_free(str);
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goto out;
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}
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g_free(str);
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str = g_strdup_printf("event-channel-%u", i);
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if (xenstore_read_fe_int(&xen_9pdev->xendev, str,
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&xen_9pdev->rings[i].evtchn) == -1) {
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g_free(str);
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goto out;
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}
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g_free(str);
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xen_9pdev->rings[i].intf =
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xen_be_map_grant_ref(&xen_9pdev->xendev,
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xen_9pdev->rings[i].ref,
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PROT_READ | PROT_WRITE);
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if (!xen_9pdev->rings[i].intf) {
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goto out;
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}
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ring_order = xen_9pdev->rings[i].intf->ring_order;
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if (ring_order > MAX_RING_ORDER) {
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goto out;
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}
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xen_9pdev->rings[i].ring_order = ring_order;
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xen_9pdev->rings[i].data =
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xen_be_map_grant_refs(&xen_9pdev->xendev,
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xen_9pdev->rings[i].intf->ref,
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(1 << ring_order),
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PROT_READ | PROT_WRITE);
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if (!xen_9pdev->rings[i].data) {
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goto out;
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}
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xen_9pdev->rings[i].ring.in = xen_9pdev->rings[i].data;
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xen_9pdev->rings[i].ring.out = xen_9pdev->rings[i].data +
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XEN_FLEX_RING_SIZE(ring_order);
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xen_9pdev->rings[i].bh = qemu_bh_new(xen_9pfs_bh, &xen_9pdev->rings[i]);
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xen_9pdev->rings[i].out_cons = 0;
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xen_9pdev->rings[i].out_size = 0;
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xen_9pdev->rings[i].inprogress = false;
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xen_9pdev->rings[i].evtchndev = xenevtchn_open(NULL, 0);
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if (xen_9pdev->rings[i].evtchndev == NULL) {
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goto out;
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}
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qemu_set_cloexec(xenevtchn_fd(xen_9pdev->rings[i].evtchndev));
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xen_9pdev->rings[i].local_port = xenevtchn_bind_interdomain
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(xen_9pdev->rings[i].evtchndev,
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xendev->dom,
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xen_9pdev->rings[i].evtchn);
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if (xen_9pdev->rings[i].local_port == -1) {
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xen_pv_printf(xendev, 0,
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"xenevtchn_bind_interdomain failed port=%d\n",
|
|
xen_9pdev->rings[i].evtchn);
|
|
goto out;
|
|
}
|
|
xen_pv_printf(xendev, 2, "bind evtchn port %d\n", xendev->local_port);
|
|
qemu_set_fd_handler(xenevtchn_fd(xen_9pdev->rings[i].evtchndev),
|
|
xen_9pfs_evtchn_event, NULL, &xen_9pdev->rings[i]);
|
|
}
|
|
|
|
xen_9pdev->security_model = xenstore_read_be_str(xendev, "security_model");
|
|
xen_9pdev->path = xenstore_read_be_str(xendev, "path");
|
|
xen_9pdev->id = s->fsconf.fsdev_id =
|
|
g_strdup_printf("xen9p%d", xendev->dev);
|
|
xen_9pdev->tag = s->fsconf.tag = xenstore_read_fe_str(xendev, "tag");
|
|
fsdev = qemu_opts_create(qemu_find_opts("fsdev"),
|
|
s->fsconf.tag,
|
|
1, NULL);
|
|
qemu_opt_set(fsdev, "fsdriver", "local", NULL);
|
|
qemu_opt_set(fsdev, "path", xen_9pdev->path, NULL);
|
|
qemu_opt_set(fsdev, "security_model", xen_9pdev->security_model, NULL);
|
|
qemu_opts_set_id(fsdev, s->fsconf.fsdev_id);
|
|
qemu_fsdev_add(fsdev, &err);
|
|
if (err) {
|
|
error_report_err(err);
|
|
}
|
|
v9fs_device_realize_common(s, &xen_9p_transport, NULL);
|
|
|
|
return 0;
|
|
|
|
out:
|
|
xen_9pfs_free(xendev);
|
|
return -1;
|
|
}
|
|
|
|
static void xen_9pfs_alloc(struct XenLegacyDevice *xendev)
|
|
{
|
|
xenstore_write_be_str(xendev, "versions", VERSIONS);
|
|
xenstore_write_be_int(xendev, "max-rings", MAX_RINGS);
|
|
xenstore_write_be_int(xendev, "max-ring-page-order", MAX_RING_ORDER);
|
|
}
|
|
|
|
struct XenDevOps xen_9pfs_ops = {
|
|
.size = sizeof(Xen9pfsDev),
|
|
.flags = DEVOPS_FLAG_NEED_GNTDEV,
|
|
.alloc = xen_9pfs_alloc,
|
|
.init = xen_9pfs_init,
|
|
.initialise = xen_9pfs_connect,
|
|
.disconnect = xen_9pfs_disconnect,
|
|
.free = xen_9pfs_free,
|
|
};
|