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drm/i915/gvt: Set SNOOP for PAT3 on BXT/APL to workaround GPU BB hang 

If guest fills non-priv bb on ApolloLake/Broxton as Mesa i965 does in:
717e7539124d (i965: Use a WC map and memcpy for the batch instead of pw-)
Due to the missing flush of bb filled by VM vCPU, host GPU hangs on
executing these MI_BATCH_BUFFER.

Temporarily workaround this by setting SNOOP bit for PAT3 used by PPGTT
PML4 PTE: PAT(0) PCD(1) PWT(1).

The performance is still expected to be low, will need further improvement.

Acked-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Signed-off-by: Colin Xu <colin.xu@intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20201012045231.226748-1-colin.xu@intel.com
This commit is contained in:
Colin Xu 2020-10-12 12:52:31 +08:00 committed by Zhenyu Wang
parent 97f9ca383d
commit 8fe1056797
1 changed files with 31 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

32
drivers/gpu/drm/i915/gvt/handlers.c
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@ -1651,6 +1651,34 @@ static int edp_psr_imr_iir_write(struct intel_vgpu *vgpu,
return 0;
}
/**
* FixMe:
* If guest fills non-priv batch buffer on ApolloLake/Broxton as Mesa i965 did:
* 717e7539124d (i965: Use a WC map and memcpy for the batch instead of pwrite.)
* Due to the missing flush of bb filled by VM vCPU, host GPU hangs on executing
* these MI_BATCH_BUFFER.
* Temporarily workaround this by setting SNOOP bit for PAT3 used by PPGTT
* PML4 PTE: PAT(0) PCD(1) PWT(1).
* The performance is still expected to be low, will need further improvement.
*/
static int bxt_ppat_low_write(struct intel_vgpu *vgpu, unsigned int offset,
void *p_data, unsigned int bytes)
{
u64 pat =
GEN8_PPAT(0, CHV_PPAT_SNOOP) |
GEN8_PPAT(1, 0) |
GEN8_PPAT(2, 0) |
GEN8_PPAT(3, CHV_PPAT_SNOOP) |
GEN8_PPAT(4, CHV_PPAT_SNOOP) |
GEN8_PPAT(5, CHV_PPAT_SNOOP) |
GEN8_PPAT(6, CHV_PPAT_SNOOP) |
GEN8_PPAT(7, CHV_PPAT_SNOOP);
vgpu_vreg(vgpu, offset) = lower_32_bits(pat);
return 0;
}
static int guc_status_read(struct intel_vgpu *vgpu,
unsigned int offset, void *p_data,
unsigned int bytes)
@ -2812,7 +2840,7 @@ static int init_bdw_mmio_info(struct intel_gvt *gvt)
MMIO_DH(GEN6_PCODE_MAILBOX, D_BDW_PLUS, NULL, mailbox_write);
MMIO_D(GEN8_PRIVATE_PAT_LO, D_BDW_PLUS);
MMIO_D(GEN8_PRIVATE_PAT_LO, D_BDW_PLUS & ~D_BXT);
MMIO_D(GEN8_PRIVATE_PAT_HI, D_BDW_PLUS);
MMIO_D(GAMTARBMODE, D_BDW_PLUS);
@ -3316,6 +3344,8 @@ static int init_bxt_mmio_info(struct intel_gvt *gvt)
MMIO_DFH(GEN9_CTX_PREEMPT_REG, D_BXT, F_CMD_ACCESS, NULL, NULL);
MMIO_DH(GEN8_PRIVATE_PAT_LO, D_BXT, NULL, bxt_ppat_low_write);
return 0;
}