On 12/5/24 06:35, Alex Williamson wrote:
> On Tue, 3 Dec 2024 21:35:42 +0800
> Tomita Moeko <[email protected]> wrote:
>
>> Add helper functions igd_gtt_memory_size() and igd_stolen_size() for
>> calculating GTT stolen memory and Data stolen memory size in bytes,
>> and use macros to replace the hardware-related magic numbers for
>> better readability.
>>
>> Signed-off-by: Tomita Moeko <[email protected]>
>> ---
>> hw/vfio/igd.c | 99 ++++++++++++++++++++++++++++-----------------------
>> 1 file changed, 55 insertions(+), 44 deletions(-)
>>
>> diff --git a/hw/vfio/igd.c b/hw/vfio/igd.c
>> index 2ede72d243..b5bfdc6580 100644
>> --- a/hw/vfio/igd.c
>> +++ b/hw/vfio/igd.c
>> @@ -106,6 +106,51 @@ typedef struct VFIOIGDQuirk {
>> #define IGD_BDSM 0x5c /* Base Data of Stolen Memory */
>> #define IGD_BDSM_GEN11 0xc0 /* Base Data of Stolen Memory of gen 11 and
>> later */
>>
>> +#define IGD_GMCH_GEN6_GMS_SHIFT 3 /* SNB_GMCH in i915 */
>> +#define IGD_GMCH_GEN6_GMS_MASK 0x1f
>> +#define IGD_GMCH_GEN6_GGMS_SHIFT 8
>> +#define IGD_GMCH_GEN6_GGMS_MASK 0x3
>> +#define IGD_GMCH_GEN8_GMS_SHIFT 8 /* BDW_GMCH in i915 */
>> +#define IGD_GMCH_GEN8_GMS_MASK 0xff
>> +#define IGD_GMCH_GEN8_GGMS_SHIFT 6
>> +#define IGD_GMCH_GEN8_GGMS_MASK 0x3
>> +
>> +static uint64_t igd_gtt_memory_size(int gen, uint16_t gmch)
>> +{
>> + uint64_t ggms;
>> +
>> + if (gen < 8) {
>> + ggms = (gmch >> IGD_GMCH_GEN6_GGMS_SHIFT) & IGD_GMCH_GEN6_GGMS_MASK;
>> + } else {
>> + ggms = (gmch >> IGD_GMCH_GEN8_GGMS_SHIFT) & IGD_GMCH_GEN8_GGMS_MASK;
>> + ggms *= 2;
>
> I tried to ask whether this was a bug fix in the previous iteration,
> but I think it was overlooked. These are not the same:
>
> ggms *= 2;
>
> ggms = 1 << ggms;
>
> Comparing the 4th processor generation datasheet[1] to that of the 5th
> generation processor[2], I see:
>
> 4th:
> 0x0 = No Preallocated Memory
> 0x1 = 1MB of Preallocated Memory
> 0x2 = 2MB of Preallocated Memory
> 0x3 = Reserved
>
> 5th:
> 0x0 = No Preallocated Memory
> 0x1 = 2MB of Preallocated Memory
> 0x2 = 4MB of Preallocated Memory
> 0x3 = 8MB of Preallocated Memory
>
> In your update, we'd get ggms values of 2, 4, and 6, which is
> incorrect. The existing code is correct to use the ggms value as the
> exponent, 2^1 = 2, 2^2 = 4, 2^3 = 8. It does seem there's a bug at
> zero though since 2^0 = 1, so maybe we should pull out the fix to a
> separate patch:
>
> if (ggms) {
> ggms = 1 << ggms;
> }
>
> Thanks,
> Alex
>
> [1]https://www.intel.com/content/dam/www/public/us/en/documents/datasheets/4th-gen-core-family-desktop-vol-2-datasheet.pdf
> (3.1.13)
> [2]https://www.intel.com/content/www/us/en/content-details/330835/5th-generation-intel-core-processor-family-volume-2-of-2-datasheet.html
> (3.1.13)
Sorry it was my mistake, the original code `1 << ggms` is correct.
I will create a new patch to fix it at first in v3. Thank you for
pointing out it.
>> + }
>> +
>> + return ggms * MiB;
>> +}
>> +
>> +static uint64_t igd_stolen_memory_size(int gen, uint32_t gmch)
>> +{
>> + uint64_t gms;
>> +
>> + if (gen < 8) {
>> + gms = (gmch >> IGD_GMCH_GEN6_GMS_SHIFT) & IGD_GMCH_GEN6_GMS_MASK;
>> + } else {
>> + gms = (gmch >> IGD_GMCH_GEN8_GMS_SHIFT) & IGD_GMCH_GEN8_GMS_MASK;
>> + }
>> +
>> + if (gen < 9) {
>> + return gms * 32 * MiB;
>> + } else {
>> + if (gms < 0xf0) {
>> + return gms * 32 * MiB;
>> + } else {
>> + return (gms - 0xf0 + 1) * 4 * MiB;
>> + }
>> + }
>> +
>> + return 0;
>> +}
>>
>> /*
>> * The rather short list of registers that we copy from the host devices.
>> @@ -254,17 +299,10 @@ static int vfio_pci_igd_lpc_init(VFIOPCIDevice *vdev,
>> 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 >= 8) {
>> - ggms = 1 << ggms;
>> - }
>> -
>> - ggms *= MiB;
>> + int gen = igd_gen(vdev);
>> + uint64_t ggms_size = igd_gtt_memory_size(gen, gmch);
>>
>> - return (ggms / (4 * KiB)) * (gen < 8 ? 4 : 8);
>> + return (ggms_size / (4 * KiB)) * (gen < 8 ? 4 : 8);
>> }
>>
>> /*
>> @@ -471,30 +509,6 @@ void vfio_probe_igd_bar0_quirk(VFIOPCIDevice *vdev, int
>> nr)
>> QLIST_INSERT_HEAD(&vdev->bars[nr].quirks, quirk, next);
>> }
>>
>> -static int igd_get_stolen_mb(int gen, uint32_t gmch)
>> -{
>> - int gms;
>> -
>> - if (gen < 8) {
>> - gms = (gmch >> 3) & 0x1f;
>> - } else {
>> - gms = (gmch >> 8) & 0xff;
>> - }
>> -
>> - if (gen < 9) {
>> - if (gms > 0x10) {
>> - error_report("Unsupported IGD GMS value 0x%x", gms);
>> - return 0;
>> - }
>> - return gms * 32;
>> - } else {
>> - if (gms < 0xf0)
>> - return gms * 32;
>> - else
>> - return (gms - 0xf0) * 4 + 4;
>> - }
>> -}
>> -
>> void vfio_probe_igd_bar4_quirk(VFIOPCIDevice *vdev, int nr)
>> {
>> g_autofree struct vfio_region_info *rom = NULL;
>> @@ -504,7 +518,8 @@ void vfio_probe_igd_bar4_quirk(VFIOPCIDevice *vdev, int
>> nr)
>> VFIOQuirk *quirk;
>> VFIOIGDQuirk *igd;
>> PCIDevice *lpc_bridge;
>> - int i, ret, ggms_mb, gms_mb = 0, gen;
>> + int i, ret, gen;
>> + uint64_t ggms_size, gms_size;
>> uint64_t *bdsm_size;
>> uint32_t gmch;
>> uint16_t cmd_orig, cmd;
>> @@ -666,13 +681,8 @@ void vfio_probe_igd_bar4_quirk(VFIOPCIDevice *vdev, int
>> nr)
>>
>> 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 >= 8) {
>> - ggms_mb = 1 << ggms_mb;
>> - }
>> -
>> - gms_mb = igd_get_stolen_mb(gen, gmch);
>> + ggms_size = igd_gtt_memory_size(gen, gmch);
>> + gms_size = igd_stolen_memory_size(gen, gmch);
>>
>> /*
>> * Request reserved memory for stolen memory via fw_cfg. VM firmware
>> @@ -683,7 +693,7 @@ void vfio_probe_igd_bar4_quirk(VFIOPCIDevice *vdev, int
>> nr)
>> * config offset 0x5C.
>> */
>> bdsm_size = g_malloc(sizeof(*bdsm_size));
>> - *bdsm_size = cpu_to_le64((ggms_mb + gms_mb) * MiB);
>> + *bdsm_size = cpu_to_le64(ggms_size + gms_size);
>> fw_cfg_add_file(fw_cfg_find(), "etc/igd-bdsm-size",
>> bdsm_size, sizeof(*bdsm_size));
>>
>> @@ -734,5 +744,6 @@ void vfio_probe_igd_bar4_quirk(VFIOPCIDevice *vdev, int
>> nr)
>> vdev->vbasedev.name);
>> }
>>
>> - trace_vfio_pci_igd_bdsm_enabled(vdev->vbasedev.name, ggms_mb + gms_mb);
>> + trace_vfio_pci_igd_bdsm_enabled(vdev->vbasedev.name,
>> + (ggms_size + gms_size) / MiB);
>> }
>
