From: Sam Bobroff <sbobr...@linux.ibm.com>

[ Upstream commit 3d0e3ce52ce3eb4b9de3caf9c38dbb5a4d3e13c3 ]

The INTERRUPT_CNTL2 register expects a valid DMA address, but is
currently set with a GPU MC address.  This can cause problems on
systems that detect the resulting DMA read from an invalid address
(found on a Power8 guest).

Instead, use the DMA address of the dummy page because it will always
be safe.

Fixes: 27ae10641e9c ("drm/amdgpu: add interupt handler implementation for si 
v3")
Signed-off-by: Sam Bobroff <sbobr...@linux.ibm.com>
Signed-off-by: Alex Deucher <alexander.deuc...@amd.com>
Signed-off-by: Sasha Levin <sas...@kernel.org>
---
 drivers/gpu/drm/amd/amdgpu/si_ih.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/si_ih.c 
b/drivers/gpu/drm/amd/amdgpu/si_ih.c
index 57bb5f9e08b2d..88ae27a5a03db 100644
--- a/drivers/gpu/drm/amd/amdgpu/si_ih.c
+++ b/drivers/gpu/drm/amd/amdgpu/si_ih.c
@@ -64,7 +64,8 @@ static int si_ih_irq_init(struct amdgpu_device *adev)
        u32 interrupt_cntl, ih_cntl, ih_rb_cntl;
 
        si_ih_disable_interrupts(adev);
-       WREG32(INTERRUPT_CNTL2, adev->irq.ih.gpu_addr >> 8);
+       /* set dummy read address to dummy page address */
+       WREG32(INTERRUPT_CNTL2, adev->dummy_page_addr >> 8);
        interrupt_cntl = RREG32(INTERRUPT_CNTL);
        interrupt_cntl &= ~IH_DUMMY_RD_OVERRIDE;
        interrupt_cntl &= ~IH_REQ_NONSNOOP_EN;
-- 
2.20.1

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