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qemu/hw/vfio/igd.c

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/*
* IGD device quirks
*
* Copyright Red Hat, Inc. 2016
*
* Authors:
* Alex Williamson <alex.williamson@redhat.com>
*
* This work is licensed under the terms of the GNU GPL, version 2. See
* the COPYING file in the top-level directory.
*/
#include "qemu/osdep.h"
#include "qemu/units.h"
#include "qapi/error.h"
#include "hw/hw.h"
#include "hw/nvram/fw_cfg.h"
#include "pci.h"
#include "trace.h"
/*
* Intel IGD support
*
* Obviously IGD is not a discrete device, this is evidenced not only by it
* being integrated into the CPU, but by the various chipset and BIOS
* dependencies that it brings along with it. Intel is trying to move away
* from this and Broadwell and newer devices can run in what Intel calls
* "Universal Pass-Through" mode, or UPT. Theoretically in UPT mode, nothing
* more is required beyond assigning the IGD device to a VM. There are
* however support limitations to this mode. It only supports IGD as a
* secondary graphics device in the VM and it doesn't officially support any
* physical outputs.
*
* The code here attempts to enable what we'll call legacy mode assignment,
* IGD retains most of the capabilities we expect for it to have on bare
* metal. To enable this mode, the IGD device must be assigned to the VM
* at PCI address 00:02.0, it must have a ROM, it very likely needs VGA
* support, we must have VM BIOS support for reserving and populating some
* of the required tables, and we need to tweak the chipset with revisions
* and IDs and an LPC/ISA bridge device. The intention is to make all of
* this happen automatically by installing the device at the correct VM PCI
* bus address. If any of the conditions are not met, we cross our fingers
* and hope the user knows better.
*
* NB - It is possible to enable physical outputs in UPT mode by supplying
* an OpRegion table. We don't do this by default because the guest driver
* behaves differently if an OpRegion is provided and no monitor is attached
* vs no OpRegion and a monitor being attached or not. Effectively, if a
* headless setup is desired, the OpRegion gets in the way of that.
*/
/*
* This presumes the device is already known to be an Intel VGA device, so we
* take liberties in which device ID bits match which generation. This should
* not be taken as an indication that all the devices are supported, or even
* supportable, some of them don't even support VT-d.
* See linux:include/drm/i915_pciids.h for IDs.
*/
static int igd_gen(VFIOPCIDevice *vdev)
{
if ((vdev->device_id & 0xfff) == 0xa84) {
return 8; /* Broxton */
}
switch (vdev->device_id & 0xff00) {
/* Old, untested, unavailable, unknown */
case 0x0000:
case 0x2500:
case 0x2700:
case 0x2900:
case 0x2a00:
case 0x2e00:
case 0x3500:
case 0xa000:
return -1;
/* SandyBridge, IvyBridge, ValleyView, Haswell */
case 0x0100:
case 0x0400:
case 0x0a00:
case 0x0c00:
case 0x0d00:
case 0x0f00:
return 6;
/* BroadWell, CherryView, SkyLake, KabyLake */
case 0x1600:
case 0x1900:
case 0x2200:
case 0x5900:
return 8;
}
return 8; /* Assume newer is compatible */
}
typedef struct VFIOIGDQuirk {
struct VFIOPCIDevice *vdev;
uint32_t index;
uint32_t bdsm;
} VFIOIGDQuirk;
#define IGD_GMCH 0x50 /* Graphics Control Register */
#define IGD_BDSM 0x5c /* Base Data of Stolen Memory */
/*
* The rather short list of registers that we copy from the host devices.
* The LPC/ISA bridge values are definitely needed to support the vBIOS, the
* host bridge values may or may not be needed depending on the guest OS.
* Since we're only munging revision and subsystem values on the host bridge,
* we don't require our own device. The LPC/ISA bridge needs to be our very
* own though.
*/
typedef struct {
uint8_t offset;
uint8_t len;
} IGDHostInfo;
static const IGDHostInfo igd_host_bridge_infos[] = {
{PCI_REVISION_ID, 2},
{PCI_SUBSYSTEM_VENDOR_ID, 2},
{PCI_SUBSYSTEM_ID, 2},
};
static const IGDHostInfo igd_lpc_bridge_infos[] = {
{PCI_VENDOR_ID, 2},
{PCI_DEVICE_ID, 2},
{PCI_REVISION_ID, 2},
{PCI_SUBSYSTEM_VENDOR_ID, 2},
{PCI_SUBSYSTEM_ID, 2},
};
static int vfio_pci_igd_copy(VFIOPCIDevice *vdev, PCIDevice *pdev,
struct vfio_region_info *info,
const IGDHostInfo *list, int len)
{
int i, ret;
for (i = 0; i < len; i++) {
ret = pread(vdev->vbasedev.fd, pdev->config + list[i].offset,
list[i].len, info->offset + list[i].offset);
if (ret != list[i].len) {
error_report("IGD copy failed: %m");
return -errno;
}
}
return 0;
}
/*
* Stuff a few values into the host bridge.
*/
static int vfio_pci_igd_host_init(VFIOPCIDevice *vdev,
struct vfio_region_info *info)
{
PCIBus *bus;
PCIDevice *host_bridge;
int ret;
bus = pci_device_root_bus(&vdev->pdev);
host_bridge = pci_find_device(bus, 0, PCI_DEVFN(0, 0));
if (!host_bridge) {
error_report("Can't find host bridge");
return -ENODEV;
}
ret = vfio_pci_igd_copy(vdev, host_bridge, info, igd_host_bridge_infos,
ARRAY_SIZE(igd_host_bridge_infos));
if (!ret) {
trace_vfio_pci_igd_host_bridge_enabled(vdev->vbasedev.name);
}
return ret;
}
/*
* IGD LPC/ISA bridge support code. The vBIOS needs this, but we can't write
* arbitrary values into just any bridge, so we must create our own. We try
* to handle if the user has created it for us, which they might want to do
* to enable multifunction so we don't occupy the whole PCI slot.
*/
static void vfio_pci_igd_lpc_bridge_realize(PCIDevice *pdev, Error **errp)
{
if (pdev->devfn != PCI_DEVFN(0x1f, 0)) {
error_setg(errp, "VFIO dummy ISA/LPC bridge must have address 1f.0");
}
}
static void vfio_pci_igd_lpc_bridge_class_init(ObjectClass *klass, void *data)
{
DeviceClass *dc = DEVICE_CLASS(klass);
PCIDeviceClass *k = PCI_DEVICE_CLASS(klass);
set_bit(DEVICE_CATEGORY_BRIDGE, dc->categories);
dc->desc = "VFIO dummy ISA/LPC bridge for IGD assignment";
dc->hotpluggable = false;
k->realize = vfio_pci_igd_lpc_bridge_realize;
k->class_id = PCI_CLASS_BRIDGE_ISA;
}
static TypeInfo vfio_pci_igd_lpc_bridge_info = {
.name = "vfio-pci-igd-lpc-bridge",
.parent = TYPE_PCI_DEVICE,
.class_init = vfio_pci_igd_lpc_bridge_class_init,
.interfaces = (InterfaceInfo[]) {
{ INTERFACE_CONVENTIONAL_PCI_DEVICE },
{ },
},
};
static void vfio_pci_igd_register_types(void)
{
type_register_static(&vfio_pci_igd_lpc_bridge_info);
}
type_init(vfio_pci_igd_register_types)
static int vfio_pci_igd_lpc_init(VFIOPCIDevice *vdev,
struct vfio_region_info *info)
{
PCIDevice *lpc_bridge;
int ret;
lpc_bridge = pci_find_device(pci_device_root_bus(&vdev->pdev),
0, PCI_DEVFN(0x1f, 0));
if (!lpc_bridge) {
lpc_bridge = pci_create_simple(pci_device_root_bus(&vdev->pdev),
PCI_DEVFN(0x1f, 0), "vfio-pci-igd-lpc-bridge");
}
ret = vfio_pci_igd_copy(vdev, lpc_bridge, info, igd_lpc_bridge_infos,
ARRAY_SIZE(igd_lpc_bridge_infos));
if (!ret) {
trace_vfio_pci_igd_lpc_bridge_enabled(vdev->vbasedev.name);
}
return ret;
}
/*
* IGD Gen8 and newer support up to 8MB for the GTT and use a 64bit PTE
* entry, older IGDs use 2MB and 32bit. Each PTE maps a 4k page. Therefore
* we either have 2M/4k * 4 = 2k or 8M/4k * 8 = 16k as the maximum iobar index
* for programming the GTT.
*
* See linux:include/drm/i915_drm.h for shift and mask values.
*/
static int vfio_igd_gtt_max(VFIOPCIDevice *vdev)
{
uint32_t gmch = vfio_pci_read_config(&vdev->pdev, IGD_GMCH, sizeof(gmch));
int ggms, gen = igd_gen(vdev);
gmch = vfio_pci_read_config(&vdev->pdev, IGD_GMCH, sizeof(gmch));
ggms = (gmch >> (gen < 8 ? 8 : 6)) & 0x3;
if (gen > 6) {
ggms = 1 << ggms;
}
ggms *= MiB;
return (ggms / (4 * KiB)) * (gen < 8 ? 4 : 8);
}
/*
* The IGD ROM will make use of stolen memory (GGMS) for support of VESA modes.
* Somehow the host stolen memory range is used for this, but how the ROM gets
* it is a mystery, perhaps it's hardcoded into the ROM. Thankfully though, it
* reprograms the GTT through the IOBAR where we can trap it and transpose the
* programming to the VM allocated buffer. That buffer gets reserved by the VM
* firmware via the fw_cfg entry added below. Here we're just monitoring the
* IOBAR address and data registers to detect a write sequence targeting the
* GTTADR. This code is developed by observed behavior and doesn't have a
* direct spec reference, unfortunately.
*/
static uint64_t vfio_igd_quirk_data_read(void *opaque,
hwaddr addr, unsigned size)
{
VFIOIGDQuirk *igd = opaque;
VFIOPCIDevice *vdev = igd->vdev;
igd->index = ~0;
return vfio_region_read(&vdev->bars[4].region, addr + 4, size);
}
static void vfio_igd_quirk_data_write(void *opaque, hwaddr addr,
uint64_t data, unsigned size)
{
VFIOIGDQuirk *igd = opaque;
VFIOPCIDevice *vdev = igd->vdev;
uint64_t val = data;
int gen = igd_gen(vdev);
/*
* Programming the GGMS starts at index 0x1 and uses every 4th index (ie.
* 0x1, 0x5, 0x9, 0xd,...). For pre-Gen8 each 4-byte write is a whole PTE
* entry, with 0th bit enable set. For Gen8 and up, PTEs are 64bit, so
* entries 0x5 & 0xd are the high dword, in our case zero. Each PTE points
* to a 4k page, which we translate to a page from the VM allocated region,
* pointed to by the BDSM register. If this is not set, we fail.
*
* We trap writes to the full configured GTT size, but we typically only
* see the vBIOS writing up to (nearly) the 1MB barrier. In fact it often
* seems to miss the last entry for an even 1MB GTT. Doing a gratuitous
* write of that last entry does work, but is hopefully unnecessary since
* we clear the previous GTT on initialization.
*/
if ((igd->index % 4 == 1) && igd->index < vfio_igd_gtt_max(vdev)) {
if (gen < 8 || (igd->index % 8 == 1)) {
uint32_t base;
base = pci_get_long(vdev->pdev.config + IGD_BDSM);
if (!base) {
hw_error("vfio-igd: Guest attempted to program IGD GTT before "
"BIOS reserved stolen memory. Unsupported BIOS?");
}
val = data - igd->bdsm + base;
} else {
val = 0; /* upper 32bits of pte, we only enable below 4G PTEs */
}
trace_vfio_pci_igd_bar4_write(vdev->vbasedev.name,
igd->index, data, val);
}
vfio_region_write(&vdev->bars[4].region, addr + 4, val, size);
igd->index = ~0;
}
static const MemoryRegionOps vfio_igd_data_quirk = {
.read = vfio_igd_quirk_data_read,
.write = vfio_igd_quirk_data_write,
.endianness = DEVICE_LITTLE_ENDIAN,
};
static uint64_t vfio_igd_quirk_index_read(void *opaque,
hwaddr addr, unsigned size)
{
VFIOIGDQuirk *igd = opaque;
VFIOPCIDevice *vdev = igd->vdev;
igd->index = ~0;
return vfio_region_read(&vdev->bars[4].region, addr, size);
}
static void vfio_igd_quirk_index_write(void *opaque, hwaddr addr,
uint64_t data, unsigned size)
{
VFIOIGDQuirk *igd = opaque;
VFIOPCIDevice *vdev = igd->vdev;
igd->index = data;
vfio_region_write(&vdev->bars[4].region, addr, data, size);
}
static const MemoryRegionOps vfio_igd_index_quirk = {
.read = vfio_igd_quirk_index_read,
.write = vfio_igd_quirk_index_write,
.endianness = DEVICE_LITTLE_ENDIAN,
};
void vfio_probe_igd_bar4_quirk(VFIOPCIDevice *vdev, int nr)
{
struct vfio_region_info *rom = NULL, *opregion = NULL,
*host = NULL, *lpc = NULL;
VFIOQuirk *quirk;
VFIOIGDQuirk *igd;
PCIDevice *lpc_bridge;
int i, ret, ggms_mb, gms_mb = 0, gen;
uint64_t *bdsm_size;
uint32_t gmch;
uint16_t cmd_orig, cmd;
Error *err = NULL;
/*
* This must be an Intel VGA device at address 00:02.0 for us to even
* consider enabling legacy mode. The vBIOS has dependencies on the
* PCI bus address.
*/
if (!vfio_pci_is(vdev, PCI_VENDOR_ID_INTEL, PCI_ANY_ID) ||
!vfio_is_vga(vdev) || nr != 4 ||
&vdev->pdev != pci_find_device(pci_device_root_bus(&vdev->pdev),
0, PCI_DEVFN(0x2, 0))) {
return;
}
/*
* We need to create an LPC/ISA bridge at PCI bus address 00:1f.0 that we
* can stuff host values into, so if there's already one there and it's not
* one we can hack on, legacy mode is no-go. Sorry Q35.
*/
lpc_bridge = pci_find_device(pci_device_root_bus(&vdev->pdev),
0, PCI_DEVFN(0x1f, 0));
if (lpc_bridge && !object_dynamic_cast(OBJECT(lpc_bridge),
"vfio-pci-igd-lpc-bridge")) {
error_report("IGD device %s cannot support legacy mode due to existing "
"devices at address 1f.0", vdev->vbasedev.name);
return;
}
/*
* IGD is not a standard, they like to change their specs often. We
* only attempt to support back to SandBridge and we hope that newer
* devices maintain compatibility with generation 8.
*/
gen = igd_gen(vdev);
if (gen != 6 && gen != 8) {
error_report("IGD device %s is unsupported in legacy mode, "
"try SandyBridge or newer", vdev->vbasedev.name);
return;
}
/*
* Most of what we're doing here is to enable the ROM to run, so if
* there's no ROM, there's no point in setting up this quirk.
* NB. We only seem to get BIOS ROMs, so a UEFI VM would need CSM support.
*/
ret = vfio_get_region_info(&vdev->vbasedev,
VFIO_PCI_ROM_REGION_INDEX, &rom);
if ((ret || !rom->size) && !vdev->pdev.romfile) {
error_report("IGD device %s has no ROM, legacy mode disabled",
vdev->vbasedev.name);
goto out;
}
/*
* Ignore the hotplug corner case, mark the ROM failed, we can't
* create the devices we need for legacy mode in the hotplug scenario.
*/
if (vdev->pdev.qdev.hotplugged) {
error_report("IGD device %s hotplugged, ROM disabled, "
"legacy mode disabled", vdev->vbasedev.name);
vdev->rom_read_failed = true;
goto out;
}
/*
* Check whether we have all the vfio device specific regions to
* support legacy mode (added in Linux v4.6). If not, bail.
*/
ret = vfio_get_dev_region_info(&vdev->vbasedev,
VFIO_REGION_TYPE_PCI_VENDOR_TYPE | PCI_VENDOR_ID_INTEL,
VFIO_REGION_SUBTYPE_INTEL_IGD_OPREGION, &opregion);
if (ret) {
error_report("IGD device %s does not support OpRegion access,"
"legacy mode disabled", vdev->vbasedev.name);
goto out;
}
ret = vfio_get_dev_region_info(&vdev->vbasedev,
VFIO_REGION_TYPE_PCI_VENDOR_TYPE | PCI_VENDOR_ID_INTEL,
VFIO_REGION_SUBTYPE_INTEL_IGD_HOST_CFG, &host);
if (ret) {
error_report("IGD device %s does not support host bridge access,"
"legacy mode disabled", vdev->vbasedev.name);
goto out;
}
ret = vfio_get_dev_region_info(&vdev->vbasedev,
VFIO_REGION_TYPE_PCI_VENDOR_TYPE | PCI_VENDOR_ID_INTEL,
VFIO_REGION_SUBTYPE_INTEL_IGD_LPC_CFG, &lpc);
if (ret) {
error_report("IGD device %s does not support LPC bridge access,"
"legacy mode disabled", vdev->vbasedev.name);
goto out;
}
gmch = vfio_pci_read_config(&vdev->pdev, IGD_GMCH, 4);
/*
* If IGD VGA Disable is clear (expected) and VGA is not already enabled,
* try to enable it. Probably shouldn't be using legacy mode without VGA,
* but also no point in us enabling VGA if disabled in hardware.
*/
if (!(gmch & 0x2) && !vdev->vga && vfio_populate_vga(vdev, &err)) {
error_reportf_err(err, VFIO_MSG_PREFIX, vdev->vbasedev.name);
error_report("IGD device %s failed to enable VGA access, "
"legacy mode disabled", vdev->vbasedev.name);
goto out;
}
/* Create our LPC/ISA bridge */
ret = vfio_pci_igd_lpc_init(vdev, lpc);
if (ret) {
error_report("IGD device %s failed to create LPC bridge, "
"legacy mode disabled", vdev->vbasedev.name);
goto out;
}
/* Stuff some host values into the VM PCI host bridge */
ret = vfio_pci_igd_host_init(vdev, host);
if (ret) {
error_report("IGD device %s failed to modify host bridge, "
"legacy mode disabled", vdev->vbasedev.name);
goto out;
}
/* Setup OpRegion access */
ret = vfio_pci_igd_opregion_init(vdev, opregion, &err);
if (ret) {
error_append_hint(&err, "IGD legacy mode disabled\n");
error_reportf_err(err, VFIO_MSG_PREFIX, vdev->vbasedev.name);
goto out;
}
/* Setup our quirk to munge GTT addresses to the VM allocated buffer */
quirk = vfio_quirk_alloc(2);
igd = quirk->data = g_malloc0(sizeof(*igd));
igd->vdev = vdev;
igd->index = ~0;
igd->bdsm = vfio_pci_read_config(&vdev->pdev, IGD_BDSM, 4);
igd->bdsm &= ~((1 * MiB) - 1); /* 1MB aligned */
memory_region_init_io(&quirk->mem[0], OBJECT(vdev), &vfio_igd_index_quirk,
igd, "vfio-igd-index-quirk", 4);
memory_region_add_subregion_overlap(vdev->bars[nr].region.mem,
0, &quirk->mem[0], 1);
memory_region_init_io(&quirk->mem[1], OBJECT(vdev), &vfio_igd_data_quirk,
igd, "vfio-igd-data-quirk", 4);
memory_region_add_subregion_overlap(vdev->bars[nr].region.mem,
4, &quirk->mem[1], 1);
QLIST_INSERT_HEAD(&vdev->bars[nr].quirks, quirk, next);
/* Determine the size of stolen memory needed for GTT */
ggms_mb = (gmch >> (gen < 8 ? 8 : 6)) & 0x3;
if (gen > 6) {
ggms_mb = 1 << ggms_mb;
}
/*
* Assume we have no GMS memory, but allow it to be overridden by device
* option (experimental). The spec doesn't actually allow zero GMS when
* when IVD (IGD VGA Disable) is clear, but the claim is that it's unused,
* so let's not waste VM memory for it.
*/
gmch &= ~((gen < 8 ? 0x1f : 0xff) << (gen < 8 ? 3 : 8));
if (vdev->igd_gms) {
if (vdev->igd_gms <= 0x10) {
gms_mb = vdev->igd_gms * 32;
gmch |= vdev->igd_gms << (gen < 8 ? 3 : 8);
} else {
error_report("Unsupported IGD GMS value 0x%x", vdev->igd_gms);
vdev->igd_gms = 0;
}
}
/*
* Request reserved memory for stolen memory via fw_cfg. VM firmware
* must allocate a 1MB aligned reserved memory region below 4GB with
* the requested size (in bytes) for use by the Intel PCI class VGA
* device at VM address 00:02.0. The base address of this reserved
* memory region must be written to the device BDSM register at PCI
* config offset 0x5C.
*/
bdsm_size = g_malloc(sizeof(*bdsm_size));
*bdsm_size = cpu_to_le64((ggms_mb + gms_mb) * MiB);
fw_cfg_add_file(fw_cfg_find(), "etc/igd-bdsm-size",
bdsm_size, sizeof(*bdsm_size));
/* GMCH is read-only, emulated */
pci_set_long(vdev->pdev.config + IGD_GMCH, gmch);
pci_set_long(vdev->pdev.wmask + IGD_GMCH, 0);
pci_set_long(vdev->emulated_config_bits + IGD_GMCH, ~0);
/* BDSM is read-write, emulated. The BIOS needs to be able to write it */
pci_set_long(vdev->pdev.config + IGD_BDSM, 0);
pci_set_long(vdev->pdev.wmask + IGD_BDSM, ~0);
pci_set_long(vdev->emulated_config_bits + IGD_BDSM, ~0);
/*
* This IOBAR gives us access to GTTADR, which allows us to write to
* the GTT itself. So let's go ahead and write zero to all the GTT
* entries to avoid spurious DMA faults. Be sure I/O access is enabled
* before talking to the device.
*/
if (pread(vdev->vbasedev.fd, &cmd_orig, sizeof(cmd_orig),
vdev->config_offset + PCI_COMMAND) != sizeof(cmd_orig)) {
error_report("IGD device %s - failed to read PCI command register",
vdev->vbasedev.name);
}
cmd = cmd_orig | PCI_COMMAND_IO;
if (pwrite(vdev->vbasedev.fd, &cmd, sizeof(cmd),
vdev->config_offset + PCI_COMMAND) != sizeof(cmd)) {
error_report("IGD device %s - failed to write PCI command register",
vdev->vbasedev.name);
}
for (i = 1; i < vfio_igd_gtt_max(vdev); i += 4) {
vfio_region_write(&vdev->bars[4].region, 0, i, 4);
vfio_region_write(&vdev->bars[4].region, 4, 0, 4);
}
if (pwrite(vdev->vbasedev.fd, &cmd_orig, sizeof(cmd_orig),
vdev->config_offset + PCI_COMMAND) != sizeof(cmd_orig)) {
error_report("IGD device %s - failed to restore PCI command register",
vdev->vbasedev.name);
}
trace_vfio_pci_igd_bdsm_enabled(vdev->vbasedev.name, ggms_mb + gms_mb);
out:
g_free(rom);
g_free(opregion);
g_free(host);
g_free(lpc);
}
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