[PATCH 2/2] hw/vfio/common: Silence ram device offset alignment error traces

Eric Auger posted 2 patches 4 months, 1 week ago
Maintainers: Alex Williamson <alex.williamson@redhat.com>, Stefan Berger <stefanb@linux.vnet.ibm.com>
[PATCH 2/2] hw/vfio/common: Silence ram device offset alignment error traces
Posted by Eric Auger 4 months, 1 week ago
Failing to DMA MAP a ram_device should not cause an error message.
This is currently happening with the TPM CRB command region and
this is causing confusion.

We may want to keep the trace for debug purpose though.

Signed-off-by: Eric Auger <eric.auger@redhat.com>

---

I am not totally clear why we do not fail on the non RAM device case
though.
---
 hw/vfio/common.c     | 15 ++++++++++++++-
 hw/vfio/trace-events |  1 +
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/hw/vfio/common.c b/hw/vfio/common.c
index 080046e3f5..9caa560b07 100644
--- a/hw/vfio/common.c
+++ b/hw/vfio/common.c
@@ -884,7 +884,20 @@ static void vfio_listener_region_add(MemoryListener *listener,
     if (unlikely((section->offset_within_address_space &
                   ~qemu_real_host_page_mask) !=
                  (section->offset_within_region & ~qemu_real_host_page_mask))) {
-        error_report("%s received unaligned region", __func__);
+        if (memory_region_is_ram_device(section->mr)) { /* just debug purpose */
+            trace_vfio_listener_region_add_bad_offset_alignment(
+                memory_region_name(section->mr),
+                section->offset_within_address_space,
+                section->offset_within_region, qemu_real_host_page_size);
+        } else { /* error case we don't want to be fatal */
+            error_report("%s received unaligned region %s iova=0x%"PRIx64
+                         " offset_within_region=0x%"PRIx64
+                         " qemu_real_host_page_mask=0x%"PRIx64,
+                         __func__, memory_region_name(section->mr),
+                         section->offset_within_address_space,
+                         section->offset_within_region,
+                         qemu_real_host_page_mask);
+        }
         return;
     }
 
diff --git a/hw/vfio/trace-events b/hw/vfio/trace-events
index 0ef1b5f4a6..ccd9d7610d 100644
--- a/hw/vfio/trace-events
+++ b/hw/vfio/trace-events
@@ -100,6 +100,7 @@ vfio_listener_region_add_skip(uint64_t start, uint64_t end) "SKIPPING region_add
 vfio_spapr_group_attach(int groupfd, int tablefd) "Attached groupfd %d to liobn fd %d"
 vfio_listener_region_add_iommu(uint64_t start, uint64_t end) "region_add [iommu] 0x%"PRIx64" - 0x%"PRIx64
 vfio_listener_region_add_ram(uint64_t iova_start, uint64_t iova_end, void *vaddr) "region_add [ram] 0x%"PRIx64" - 0x%"PRIx64" [%p]"
+vfio_listener_region_add_bad_offset_alignment(const char *name, uint64_t iova, uint64_t offset_within_region, uint64_t page_size) "Region \"%s\" @0x%"PRIx64", offset_within_region=0x%"PRIx64", qemu_real_host_page_mask=0x%"PRIx64 " cannot be mapped for DMA"
 vfio_listener_region_add_no_dma_map(const char *name, uint64_t iova, uint64_t size, uint64_t page_size) "Region \"%s\" 0x%"PRIx64" size=0x%"PRIx64" is not aligned to 0x%"PRIx64" and cannot be mapped for DMA"
 vfio_listener_region_del_skip(uint64_t start, uint64_t end) "SKIPPING region_del 0x%"PRIx64" - 0x%"PRIx64
 vfio_listener_region_del(uint64_t start, uint64_t end) "region_del 0x%"PRIx64" - 0x%"PRIx64
-- 
2.26.3


Re: [PATCH 2/2] hw/vfio/common: Silence ram device offset alignment error traces
Posted by Stefan Berger 4 months, 1 week ago
On 1/13/22 05:37, Eric Auger wrote:
> Failing to DMA MAP a ram_device should not cause an error message.
> This is currently happening with the TPM CRB command region and
> this is causing confusion.
>
> We may want to keep the trace for debug purpose though.
>
> Signed-off-by: Eric Auger <eric.auger@redhat.com>

Tested-by: Stefan Berger <stefanb@linux.ibm.com>


>
> ---
>
> I am not totally clear why we do not fail on the non RAM device case
> though.
> ---
>   hw/vfio/common.c     | 15 ++++++++++++++-
>   hw/vfio/trace-events |  1 +
>   2 files changed, 15 insertions(+), 1 deletion(-)
>
> diff --git a/hw/vfio/common.c b/hw/vfio/common.c
> index 080046e3f5..9caa560b07 100644
> --- a/hw/vfio/common.c
> +++ b/hw/vfio/common.c
> @@ -884,7 +884,20 @@ static void vfio_listener_region_add(MemoryListener *listener,
>       if (unlikely((section->offset_within_address_space &
>                     ~qemu_real_host_page_mask) !=
>                    (section->offset_within_region & ~qemu_real_host_page_mask))) {
> -        error_report("%s received unaligned region", __func__);
> +        if (memory_region_is_ram_device(section->mr)) { /* just debug purpose */
> +            trace_vfio_listener_region_add_bad_offset_alignment(
> +                memory_region_name(section->mr),
> +                section->offset_within_address_space,
> +                section->offset_within_region, qemu_real_host_page_size);
> +        } else { /* error case we don't want to be fatal */
> +            error_report("%s received unaligned region %s iova=0x%"PRIx64
> +                         " offset_within_region=0x%"PRIx64
> +                         " qemu_real_host_page_mask=0x%"PRIx64,
> +                         __func__, memory_region_name(section->mr),
> +                         section->offset_within_address_space,
> +                         section->offset_within_region,
> +                         qemu_real_host_page_mask);
> +        }
>           return;
>       }
>
> diff --git a/hw/vfio/trace-events b/hw/vfio/trace-events
> index 0ef1b5f4a6..ccd9d7610d 100644
> --- a/hw/vfio/trace-events
> +++ b/hw/vfio/trace-events
> @@ -100,6 +100,7 @@ vfio_listener_region_add_skip(uint64_t start, uint64_t end) "SKIPPING region_add
>   vfio_spapr_group_attach(int groupfd, int tablefd) "Attached groupfd %d to liobn fd %d"
>   vfio_listener_region_add_iommu(uint64_t start, uint64_t end) "region_add [iommu] 0x%"PRIx64" - 0x%"PRIx64
>   vfio_listener_region_add_ram(uint64_t iova_start, uint64_t iova_end, void *vaddr) "region_add [ram] 0x%"PRIx64" - 0x%"PRIx64" [%p]"
> +vfio_listener_region_add_bad_offset_alignment(const char *name, uint64_t iova, uint64_t offset_within_region, uint64_t page_size) "Region \"%s\" @0x%"PRIx64", offset_within_region=0x%"PRIx64", qemu_real_host_page_mask=0x%"PRIx64 " cannot be mapped for DMA"
>   vfio_listener_region_add_no_dma_map(const char *name, uint64_t iova, uint64_t size, uint64_t page_size) "Region \"%s\" 0x%"PRIx64" size=0x%"PRIx64" is not aligned to 0x%"PRIx64" and cannot be mapped for DMA"
>   vfio_listener_region_del_skip(uint64_t start, uint64_t end) "SKIPPING region_del 0x%"PRIx64" - 0x%"PRIx64
>   vfio_listener_region_del(uint64_t start, uint64_t end) "region_del 0x%"PRIx64" - 0x%"PRIx64