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vfio-pci: Generalize PCI config mangling 

Kernel-side vfio virtualizes all of config space, but some parts are
unique to Qemu.  For instance we may or may not expose the ROM BAR,
Qemu manages MSI/MSIX, and Qemu manages the multi-function bit so that
single function devices can appear as multi-function and vica versa.
Generalize this into a bitmap of Qemu emulated bits.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
This commit is contained in:
Alex Williamson 2013-04-01 11:50:04 -06:00
parent 010ca0b3fb
commit 4b5d5e87c7
1 changed files with 42 additions and 38 deletions
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80
hw/vfio_pci.c
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@ -117,6 +117,7 @@ typedef struct VFIODevice {
int fd;
VFIOINTx intx;
unsigned int config_size;
uint8_t *emulated_config_bits; /* QEMU emulated bits, little-endian */
off_t config_offset; /* Offset of config space region within device fd */
unsigned int rom_size;
off_t rom_offset; /* Offset of ROM region within device fd */
@ -963,44 +964,29 @@ static const MemoryRegionOps vfio_bar_ops = {
static uint32_t vfio_pci_read_config(PCIDevice *pdev, uint32_t addr, int len)
{
VFIODevice *vdev = DO_UPCAST(VFIODevice, pdev, pdev);
uint32_t val = 0;
uint32_t emu_bits = 0, emu_val = 0, phys_val = 0, val;
/*
* We only need QEMU PCI config support for the ROM BAR, the MSI and MSIX
* capabilities, and the multifunction bit below. We let VFIO handle
* virtualizing everything else. Performance is not a concern here.
*/
if (ranges_overlap(addr, len, PCI_ROM_ADDRESS, 4) ||
(pdev->cap_present & QEMU_PCI_CAP_MSIX &&
ranges_overlap(addr, len, pdev->msix_cap, MSIX_CAP_LENGTH)) ||
(pdev->cap_present & QEMU_PCI_CAP_MSI &&
ranges_overlap(addr, len, pdev->msi_cap, vdev->msi_cap_size))) {
memcpy(&emu_bits, vdev->emulated_config_bits + addr, len);
emu_bits = le32_to_cpu(emu_bits);
val = pci_default_read_config(pdev, addr, len);
} else {
if (pread(vdev->fd, &val, len, vdev->config_offset + addr) != len) {
if (emu_bits) {
emu_val = pci_default_read_config(pdev, addr, len);
}
if (~emu_bits & (0xffffffffU >> (32 - len * 8))) {
ssize_t ret;
ret = pread(vdev->fd, &phys_val, len, vdev->config_offset + addr);
if (ret != len) {
error_report("%s(%04x:%02x:%02x.%x, 0x%x, 0x%x) failed: %m",
__func__, vdev->host.domain, vdev->host.bus,
vdev->host.slot, vdev->host.function, addr, len);
return -errno;
}
val = le32_to_cpu(val);
phys_val = le32_to_cpu(phys_val);
}
/* Multifunction bit is virualized in QEMU */
if (unlikely(ranges_overlap(addr, len, PCI_HEADER_TYPE, 1))) {
uint32_t mask = PCI_HEADER_TYPE_MULTI_FUNCTION;
if (len == 4) {
mask <<= 16;
}
if (pdev->cap_present & QEMU_PCI_CAP_MULTIFUNCTION) {
val |= mask;
} else {
val &= ~mask;
}
}
val = (emu_val & emu_bits) | (phys_val & ~emu_bits);
DPRINTF("%s(%04x:%02x:%02x.%x, @0x%x, len=0x%x) %x\n", __func__,
vdev->host.domain, vdev->host.bus, vdev->host.slot,
@ -1026,12 +1012,6 @@ static void vfio_pci_write_config(PCIDevice *pdev, uint32_t addr,
vdev->host.slot, vdev->host.function, addr, val, len);
}
/* Write standard header bits to emulation */
if (addr < PCI_CONFIG_HEADER_SIZE) {
pci_default_write_config(pdev, addr, val, len);
return;
}
/* MSI/MSI-X Enabling/Disabling */
if (pdev->cap_present & QEMU_PCI_CAP_MSI &&
ranges_overlap(addr, len, pdev->msi_cap, vdev->msi_cap_size)) {
@ -1046,9 +1026,7 @@ static void vfio_pci_write_config(PCIDevice *pdev, uint32_t addr,
} else if (was_enabled && !is_enabled) {
vfio_disable_msi(vdev);
}
}
if (pdev->cap_present & QEMU_PCI_CAP_MSIX &&
} else if (pdev->cap_present & QEMU_PCI_CAP_MSIX &&
ranges_overlap(addr, len, pdev->msix_cap, MSIX_CAP_LENGTH)) {
int is_enabled, was_enabled = msix_enabled(pdev);
@ -1061,6 +1039,9 @@ static void vfio_pci_write_config(PCIDevice *pdev, uint32_t addr,
} else if (was_enabled && !is_enabled) {
vfio_disable_msix(vdev);
}
} else {
/* Write everything to QEMU to keep emulated bits correct */
pci_default_write_config(pdev, addr, val, len);
}
}
@ -2003,6 +1984,16 @@ static int vfio_initfn(PCIDevice *pdev)
goto out_put;
}
/* vfio emulates a lot for us, but some bits need extra love */
vdev->emulated_config_bits = g_malloc0(vdev->config_size);
/* QEMU can choose to expose the ROM or not */
memset(vdev->emulated_config_bits + PCI_ROM_ADDRESS, 0xff, 4);
/* QEMU can change multi-function devices to single function, or reverse */
vdev->emulated_config_bits[PCI_HEADER_TYPE] =
PCI_HEADER_TYPE_MULTI_FUNCTION;
/*
* Clear host resource mapping info. If we choose not to register a
* BAR, such as might be the case with the option ROM, we can get
@ -2025,6 +2016,17 @@ static int vfio_initfn(PCIDevice *pdev)
goto out_teardown;
}
/* QEMU emulates all of MSI & MSIX */
if (pdev->cap_present & QEMU_PCI_CAP_MSIX) {
memset(vdev->emulated_config_bits + pdev->msix_cap, 0xff,
MSIX_CAP_LENGTH);
}
if (pdev->cap_present & QEMU_PCI_CAP_MSI) {
memset(vdev->emulated_config_bits + pdev->msi_cap, 0xff,
vdev->msi_cap_size);
}
if (vfio_pci_read_config(&vdev->pdev, PCI_INTERRUPT_PIN, 1)) {
vdev->intx.mmap_timer = qemu_new_timer_ms(vm_clock,
vfio_intx_mmap_enable, vdev);
@ -2042,6 +2044,7 @@ out_teardown:
vfio_teardown_msi(vdev);
vfio_unmap_bars(vdev);
out_put:
g_free(vdev->emulated_config_bits);
vfio_put_device(vdev);
vfio_put_group(group);
return ret;
@ -2059,6 +2062,7 @@ static void vfio_exitfn(PCIDevice *pdev)
}
vfio_teardown_msi(vdev);
vfio_unmap_bars(vdev);
g_free(vdev->emulated_config_bits);
vfio_put_device(vdev);
vfio_put_group(group);
}