Re: Upstream Dom0 DRM problems regarding swiotlb

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Wed, Feb 13, 2019 at 09:09:32AM -0700, Jan Beulich wrote:
> >>> On 13.02.19 at 17:00, <michael.d.labriola@gmail.com> wrote:
> > On Wed, Feb 13, 2019 at 9:28 AM Jan Beulich <JBeulich@suse.com> wrote:
> >> >>> On 13.02.19 at 15:10, <michael.d.labriola@gmail.com> wrote:
> >> > Ah, so this isn't necessarily Xen-specific but rather any paravirtual
> >> > guest?  That hadn't crossed my mind.  Is there an easy way to find out
> >> > if we're a pv guest in the need_swiotlb conditionals?
> >>
> >> There's xen_pv_domain(), but I think xen_swiotlb would be more to
> >> the point if the check is already to be Xen-specific. There's no generic
> >> "is PV" predicate that I'm aware of.
> > 
> > Well, that makes doing conditional code right more difficult.  I
> > assume since there isn't a generic predicate, and PV isn't new, that
> > it's absence is by design?  To reign in the temptation to sprinkle
> > conditional code all over the kernel?  ;-)
> 
> Well, with lguest gone, Xen is the only PV environment the kernel
> can run in, afaik at least. I guess to decide between the suggested
> options or the need for some abstracting macro (or yet something
> else), you'll really need to ask the driver maintainers. Or simply
> send a patch their way implementing one of them, and see what
> their reaction is.

Could you try this out and see if it works and I will send it out:



diff --git a/drivers/gpu/drm/amd/amdgpu/gmc_v6_0.c b/drivers/gpu/drm/amd/amdgpu/gmc_v6_0.c
index 9fc3296592fe..96bf1df0ed28 100644
--- a/drivers/gpu/drm/amd/amdgpu/gmc_v6_0.c
+++ b/drivers/gpu/drm/amd/amdgpu/gmc_v6_0.c
@@ -23,6 +23,7 @@
 #include <linux/firmware.h>
 #include <drm/drmP.h>
 #include <drm/drm_cache.h>
+#include <xen/xen.h>
 #include "amdgpu.h"
 #include "gmc_v6_0.h"
 #include "amdgpu_ucode.h"
@@ -887,6 +888,8 @@ static int gmc_v6_0_sw_init(void *handle)
 		dev_warn(adev->dev, "amdgpu: No coherent DMA available.\n");
 	}
 	adev->need_swiotlb = drm_get_max_iomem() > ((u64)1 << dma_bits);
+	if (xen_pv_domain())
+		adev->need_swiotlb = 1;
 
 	r = gmc_v6_0_init_microcode(adev);
 	if (r) {
diff --git a/drivers/gpu/drm/amd/amdgpu/gmc_v7_0.c b/drivers/gpu/drm/amd/amdgpu/gmc_v7_0.c
index 761dcfb2fec0..710ac0ece1b0 100644
--- a/drivers/gpu/drm/amd/amdgpu/gmc_v7_0.c
+++ b/drivers/gpu/drm/amd/amdgpu/gmc_v7_0.c
@@ -23,6 +23,7 @@
 #include <linux/firmware.h>
 #include <drm/drmP.h>
 #include <drm/drm_cache.h>
+#include <xen/xen.h>
 #include "amdgpu.h"
 #include "cikd.h"
 #include "cik.h"
@@ -1031,6 +1032,8 @@ static int gmc_v7_0_sw_init(void *handle)
 		pr_warn("amdgpu: No coherent DMA available\n");
 	}
 	adev->need_swiotlb = drm_get_max_iomem() > ((u64)1 << dma_bits);
+	if (xen_pv_domain())
+		adev->need_swiotlb = 1;
 
 	r = gmc_v7_0_init_microcode(adev);
 	if (r) {
diff --git a/drivers/gpu/drm/amd/amdgpu/gmc_v8_0.c b/drivers/gpu/drm/amd/amdgpu/gmc_v8_0.c
index 1ad7e6b8ed1d..c418a129bb32 100644
--- a/drivers/gpu/drm/amd/amdgpu/gmc_v8_0.c
+++ b/drivers/gpu/drm/amd/amdgpu/gmc_v8_0.c
@@ -23,6 +23,7 @@
 #include <linux/firmware.h>
 #include <drm/drmP.h>
 #include <drm/drm_cache.h>
+#include <xen/xen.h>
 #include "amdgpu.h"
 #include "gmc_v8_0.h"
 #include "amdgpu_ucode.h"
@@ -1156,6 +1157,8 @@ static int gmc_v8_0_sw_init(void *handle)
 		pr_warn("amdgpu: No coherent DMA available\n");
 	}
 	adev->need_swiotlb = drm_get_max_iomem() > ((u64)1 << dma_bits);
+	if (xen_pv_domain())
+		adev->need_swiotlb = 1;
 
 	r = gmc_v8_0_init_microcode(adev);
 	if (r) {
diff --git a/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c b/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c
index bacdaef77b6c..85c0762c37ae 100644
--- a/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c
+++ b/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c
@@ -22,6 +22,7 @@
  */
 #include <linux/firmware.h>
 #include <drm/drm_cache.h>
+#include <xen/xen.h>
 #include "amdgpu.h"
 #include "gmc_v9_0.h"
 #include "amdgpu_atomfirmware.h"
@@ -1004,6 +1005,8 @@ static int gmc_v9_0_sw_init(void *handle)
 		printk(KERN_WARNING "amdgpu: No coherent DMA available.\n");
 	}
 	adev->need_swiotlb = drm_get_max_iomem() > ((u64)1 << dma_bits);
+	if (xen_pv_domain())
+		adev->need_swiotlb = 1;
 
 	if (adev->gmc.xgmi.supported) {
 		r = gfxhub_v1_1_get_xgmi_info(adev);
diff --git a/drivers/gpu/drm/radeon/radeon_device.c b/drivers/gpu/drm/radeon/radeon_device.c
index 59c8a6647ff2..02fba6829936 100644
--- a/drivers/gpu/drm/radeon/radeon_device.c
+++ b/drivers/gpu/drm/radeon/radeon_device.c
@@ -35,6 +35,7 @@
 #include <linux/vgaarb.h>
 #include <linux/vga_switcheroo.h>
 #include <linux/efi.h>
+#include <xen/xen.h>
 #include "radeon_reg.h"
 #include "radeon.h"
 #include "atom.h"
@@ -1388,6 +1389,8 @@ int radeon_device_init(struct radeon_device *rdev,
 		pr_warn("radeon: No coherent DMA available\n");
 	}
 	rdev->need_swiotlb = drm_get_max_iomem() > ((u64)1 << dma_bits);
+	if (xen_pv_domain())
+		rdev->need_swiotlb = 1;
 
 	/* Registers mapping */
 	/* TODO: block userspace mapping of io register */

> 
> Jan
> 
> 

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