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virtio-pci: Replace modern_as with direct access to modern_bar 

The modern bar is accessed now via yet another address space created just
for that purpose and it does not really need FlatView and dispatch tree
as it has a single memory region so it is just a waste of memory. Things
get even worse when there are dozens or hundreds of virtio-pci devices -
since these address spaces are global, changing any of them triggers
rebuilding all address spaces.

This replaces indirect accesses to the modern BAR with a simple lookup
and direct calls to memory_region_dispatch_read/write.

This is expected to save lots of memory at boot time after applying:
[Qemu-devel] [PULL 00/32] Misc changes for 2017-09-22

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Alexey Kardashevskiy 2017-10-09 14:19:41 +11:00 committed by Michael S. Tsirkin
parent 37ef70be6a
commit a93c8d828a
2 changed files with 54 additions and 38 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

75
hw/virtio/virtio-pci.c
View File

@ -491,6 +491,24 @@ static const MemoryRegionOps virtio_pci_config_ops = {
.endianness = DEVICE_LITTLE_ENDIAN,
};
static MemoryRegion *virtio_address_space_lookup(VirtIOPCIProxy *proxy,
hwaddr *off, int len)
{
int i;
VirtIOPCIRegion *reg;
for (i = 0; i < ARRAY_SIZE(proxy->regs); ++i) {
reg = &proxy->regs[i];
if (*off >= reg->offset &&
*off + len <= reg->offset + reg->size) {
*off -= reg->offset;
return &reg->mr;
}
}
return NULL;
}
/* Below are generic functions to do memcpy from/to an address space,
* without byteswaps, with input validation.
*
@ -504,63 +522,72 @@ static const MemoryRegionOps virtio_pci_config_ops = {
* Note: host pointer must be aligned.
*/
static
void virtio_address_space_write(AddressSpace *as, hwaddr addr,
void virtio_address_space_write(VirtIOPCIProxy *proxy, hwaddr addr,
const uint8_t *buf, int len)
{
uint32_t val;
uint64_t val;
MemoryRegion *mr;
/* address_space_* APIs assume an aligned address.
* As address is under guest control, handle illegal values.
*/
addr &= ~(len - 1);
mr = virtio_address_space_lookup(proxy, &addr, len);
if (!mr) {
return;
}
/* Make sure caller aligned buf properly */
assert(!(((uintptr_t)buf) & (len - 1)));
switch (len) {
case 1:
val = pci_get_byte(buf);
address_space_stb(as, addr, val, MEMTXATTRS_UNSPECIFIED, NULL);
break;
case 2:
val = pci_get_word(buf);
address_space_stw_le(as, addr, val, MEMTXATTRS_UNSPECIFIED, NULL);
val = cpu_to_le16(pci_get_word(buf));
break;
case 4:
val = pci_get_long(buf);
address_space_stl_le(as, addr, val, MEMTXATTRS_UNSPECIFIED, NULL);
val = cpu_to_le32(pci_get_long(buf));
break;
default:
/* As length is under guest control, handle illegal values. */
break;
return;
}
memory_region_dispatch_write(mr, addr, val, len, MEMTXATTRS_UNSPECIFIED);
}
static void
virtio_address_space_read(AddressSpace *as, hwaddr addr, uint8_t *buf, int len)
virtio_address_space_read(VirtIOPCIProxy *proxy, hwaddr addr,
uint8_t *buf, int len)
{
uint32_t val;
uint64_t val;
MemoryRegion *mr;
/* address_space_* APIs assume an aligned address.
* As address is under guest control, handle illegal values.
*/
addr &= ~(len - 1);
mr = virtio_address_space_lookup(proxy, &addr, len);
if (!mr) {
return;
}
/* Make sure caller aligned buf properly */
assert(!(((uintptr_t)buf) & (len - 1)));
memory_region_dispatch_read(mr, addr, &val, len, MEMTXATTRS_UNSPECIFIED);
switch (len) {
case 1:
val = address_space_ldub(as, addr, MEMTXATTRS_UNSPECIFIED, NULL);
pci_set_byte(buf, val);
break;
case 2:
val = address_space_lduw_le(as, addr, MEMTXATTRS_UNSPECIFIED, NULL);
pci_set_word(buf, val);
pci_set_word(buf, le16_to_cpu(val));
break;
case 4:
val = address_space_ldl_le(as, addr, MEMTXATTRS_UNSPECIFIED, NULL);
pci_set_long(buf, val);
pci_set_long(buf, le32_to_cpu(val));
break;
default:
/* As length is under guest control, handle illegal values. */
@ -596,8 +623,7 @@ static void virtio_write_config(PCIDevice *pci_dev, uint32_t address,
if (len == 1 || len == 2 || len == 4) {
assert(len <= sizeof cfg->pci_cfg_data);
virtio_address_space_write(&proxy->modern_as, off,
cfg->pci_cfg_data, len);
virtio_address_space_write(proxy, off, cfg->pci_cfg_data, len);
}
}
}
@ -621,8 +647,7 @@ static uint32_t virtio_read_config(PCIDevice *pci_dev,
if (len == 1 || len == 2 || len == 4) {
assert(len <= sizeof cfg->pci_cfg_data);
virtio_address_space_read(&proxy->modern_as, off,
cfg->pci_cfg_data, len);
virtio_address_space_read(proxy, off, cfg->pci_cfg_data, len);
}
}
@ -1729,15 +1754,6 @@ static void virtio_pci_realize(PCIDevice *pci_dev, Error **errp)
/* PCI BAR regions must be powers of 2 */
pow2ceil(proxy->notify.offset + proxy->notify.size));
memory_region_init_alias(&proxy->modern_cfg,
OBJECT(proxy),
"virtio-pci-cfg",
&proxy->modern_bar,
0,
memory_region_size(&proxy->modern_bar));
address_space_init(&proxy->modern_as, &proxy->modern_cfg, "virtio-pci-cfg-as");
if (proxy->disable_legacy == ON_OFF_AUTO_AUTO) {
proxy->disable_legacy = pcie_port ? ON_OFF_AUTO_ON : ON_OFF_AUTO_OFF;
}
@ -1806,10 +1822,7 @@ static void virtio_pci_realize(PCIDevice *pci_dev, Error **errp)
static void virtio_pci_exit(PCIDevice *pci_dev)
{
VirtIOPCIProxy *proxy = VIRTIO_PCI(pci_dev);
msix_uninit_exclusive_bar(pci_dev);
address_space_destroy(&proxy->modern_as);
}
static void virtio_pci_reset(DeviceState *qdev)

17
hw/virtio/virtio-pci.h
View File

@ -155,15 +155,18 @@ typedef struct VirtIOPCIQueue {
struct VirtIOPCIProxy {
PCIDevice pci_dev;
MemoryRegion bar;
VirtIOPCIRegion common;
VirtIOPCIRegion isr;
VirtIOPCIRegion device;
VirtIOPCIRegion notify;
VirtIOPCIRegion notify_pio;
union {
struct {
VirtIOPCIRegion common;
VirtIOPCIRegion isr;
VirtIOPCIRegion device;
VirtIOPCIRegion notify;
VirtIOPCIRegion notify_pio;
};
VirtIOPCIRegion regs[5];
};
MemoryRegion modern_bar;
MemoryRegion io_bar;
MemoryRegion modern_cfg;
AddressSpace modern_as;
uint32_t legacy_io_bar_idx;
uint32_t msix_bar_idx;
uint32_t modern_io_bar_idx;