hw/xen: Support mapping grant frames

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Paul Durrant <paul@xen.org>
This commit is contained in:
David Woodhouse 2022-12-16 18:33:49 +00:00
parent a28b0fc034
commit e33cb789af
3 changed files with 75 additions and 2 deletions

View File

@ -37,13 +37,26 @@ OBJECT_DECLARE_SIMPLE_TYPE(XenGnttabState, XEN_GNTTAB)
#define XEN_PAGE_SHIFT 12
#define XEN_PAGE_SIZE (1ULL << XEN_PAGE_SHIFT)
#define ENTRIES_PER_FRAME_V1 (XEN_PAGE_SIZE / sizeof(grant_entry_v1_t))
struct XenGnttabState {
/*< private >*/
SysBusDevice busdev;
/*< public >*/
QemuMutex gnt_lock;
uint32_t nr_frames;
uint32_t max_frames;
union {
grant_entry_v1_t *v1;
/* Theoretically, v2 support could be added here. */
} entries;
MemoryRegion gnt_frames;
MemoryRegion *gnt_aliases;
uint64_t *gnt_frame_gpas;
};
struct XenGnttabState *xen_gnttab_singleton;
@ -51,6 +64,7 @@ struct XenGnttabState *xen_gnttab_singleton;
static void xen_gnttab_realize(DeviceState *dev, Error **errp)
{
XenGnttabState *s = XEN_GNTTAB(dev);
int i;
if (xen_mode != XEN_EMULATE) {
error_setg(errp, "Xen grant table support is for Xen emulation");
@ -58,6 +72,38 @@ static void xen_gnttab_realize(DeviceState *dev, Error **errp)
}
s->nr_frames = 0;
s->max_frames = kvm_xen_get_gnttab_max_frames();
memory_region_init_ram(&s->gnt_frames, OBJECT(dev), "xen:grant_table",
XEN_PAGE_SIZE * s->max_frames, &error_abort);
memory_region_set_enabled(&s->gnt_frames, true);
s->entries.v1 = memory_region_get_ram_ptr(&s->gnt_frames);
memset(s->entries.v1, 0, XEN_PAGE_SIZE * s->max_frames);
/* Create individual page-sizes aliases for overlays */
s->gnt_aliases = (void *)g_new0(MemoryRegion, s->max_frames);
s->gnt_frame_gpas = (void *)g_new(uint64_t, s->max_frames);
for (i = 0; i < s->max_frames; i++) {
memory_region_init_alias(&s->gnt_aliases[i], OBJECT(dev),
NULL, &s->gnt_frames,
i * XEN_PAGE_SIZE, XEN_PAGE_SIZE);
s->gnt_frame_gpas[i] = INVALID_GPA;
}
qemu_mutex_init(&s->gnt_lock);
xen_gnttab_singleton = s;
}
static int xen_gnttab_post_load(void *opaque, int version_id)
{
XenGnttabState *s = XEN_GNTTAB(opaque);
uint32_t i;
for (i = 0; i < s->nr_frames; i++) {
if (s->gnt_frame_gpas[i] != INVALID_GPA) {
xen_overlay_do_map_page(&s->gnt_aliases[i], s->gnt_frame_gpas[i]);
}
}
return 0;
}
static bool xen_gnttab_is_needed(void *opaque)
@ -70,8 +116,11 @@ static const VMStateDescription xen_gnttab_vmstate = {
.version_id = 1,
.minimum_version_id = 1,
.needed = xen_gnttab_is_needed,
.post_load = xen_gnttab_post_load,
.fields = (VMStateField[]) {
VMSTATE_UINT32(nr_frames, XenGnttabState),
VMSTATE_VARRAY_UINT32(gnt_frame_gpas, XenGnttabState, nr_frames, 0,
vmstate_info_uint64, uint64_t),
VMSTATE_END_OF_LIST()
}
};
@ -106,6 +155,28 @@ type_init(xen_gnttab_register_types)
int xen_gnttab_map_page(uint64_t idx, uint64_t gfn)
{
return -ENOSYS;
XenGnttabState *s = xen_gnttab_singleton;
uint64_t gpa = gfn << XEN_PAGE_SHIFT;
if (!s) {
return -ENOTSUP;
}
if (idx >= s->max_frames) {
return -EINVAL;
}
QEMU_IOTHREAD_LOCK_GUARD();
QEMU_LOCK_GUARD(&s->gnt_lock);
xen_overlay_do_map_page(&s->gnt_aliases[idx], gpa);
s->gnt_frame_gpas[idx] = gpa;
if (s->nr_frames <= idx) {
s->nr_frames = idx + 1;
}
return 0;
}

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@ -49,7 +49,7 @@ struct XenOverlayState {
struct XenOverlayState *xen_overlay_singleton;
static void xen_overlay_do_map_page(MemoryRegion *page, uint64_t gpa)
void xen_overlay_do_map_page(MemoryRegion *page, uint64_t gpa)
{
/*
* Xen allows guests to map the same page as many times as it likes

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@ -21,4 +21,6 @@ int xen_sync_long_mode(void);
int xen_set_long_mode(bool long_mode);
bool xen_is_long_mode(void);
void xen_overlay_do_map_page(MemoryRegion *page, uint64_t gpa);
#endif /* QEMU_XEN_OVERLAY_H */