On Wed, 23 Mar 2022 21:31:19 +0100
Eric Auger <eric.au...@redhat.com> wrote:
> The CRB command buffer currently is a RAM MemoryRegion and given
> its base address alignment, it causes an error report on
> vfio_listener_region_add(). This region could have been a RAM device
> region, easing the detection of such safe situation but this option
> was not well received. So let's add a helper function that uses the
> memory region owner type to detect the situation is safe wrt
> the assignment. Other device types can be checked here if such kind
> of problem occurs again.
>
> Signed-off-by: Eric Auger <eric.au...@redhat.com>
> Reviewed-by: Philippe Mathieu-Daudé <f4...@amsat.org>
>
> ---
>
> v2 -> v3:
> - Use TPM_IS_CRB()
>
> v1 -> v2:
> - do not check the MR name but rather the owner type
> ---
> hw/vfio/common.c | 27 ++++++++++++++++++++++++++-
> hw/vfio/trace-events | 1 +
> 2 files changed, 27 insertions(+), 1 deletion(-)
>
> diff --git a/hw/vfio/common.c b/hw/vfio/common.c
> index 080046e3f51..55bc116473e 100644
> --- a/hw/vfio/common.c
> +++ b/hw/vfio/common.c
> @@ -40,6 +40,7 @@
> #include "trace.h"
> #include "qapi/error.h"
> #include "migration/migration.h"
> +#include "sysemu/tpm.h"
>
> VFIOGroupList vfio_group_list =
> QLIST_HEAD_INITIALIZER(vfio_group_list);
> @@ -861,6 +862,22 @@ static void
> vfio_unregister_ram_discard_listener(VFIOContainer *container,
> g_free(vrdl);
> }
>
> +static bool vfio_known_safe_misalignment(MemoryRegionSection *section)
> +{
> + MemoryRegion *mr = section->mr;
> +
> + if (!TPM_IS_CRB(mr->owner)) {
> + return false;
> + }
> +
> + /* this is a known safe misaligned region, just trace for debug purpose
> */
> + trace_vfio_known_safe_misalignment(memory_region_name(mr),
> + section->offset_within_address_space,
> + section->offset_within_region,
> + qemu_real_host_page_size);
qemu_real_host_page_size and qemu_real_host_page_mask are now functions.
I thought I'd just append "()" in each case, but then the 32-bit build
breaks...
> + return true;
> +}
> +
> static void vfio_listener_region_add(MemoryListener *listener,
> MemoryRegionSection *section)
> {
> @@ -884,7 +901,15 @@ 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 (!vfio_known_safe_misalignment(section)) {
> + error_report("%s received unaligned region %s iova=0x%"PRIx64
> + " offset_within_region=0x%"PRIx64
> + " qemu_real_host_page_mask=0x%"PRIxPTR,
> + __func__, memory_region_name(section->mr),
> + section->offset_within_address_space,
> + section->offset_within_region,
> + qemu_real_host_page_mask);
Note how here we're very verbosely printing
"qemu_real_host_page_mask=0x%..." and we're passing the
qemu_real_host_page_mask value. In the previous trace command we're
passing qemu_real_host_page_size.
> + }
> return;
> }
>
> diff --git a/hw/vfio/trace-events b/hw/vfio/trace-events
> index 0ef1b5f4a65..6f38a2e6991 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_known_safe_misalignment(const char *name, uint64_t iova, uint64_t
> offset_within_region, uint64_t page_size) "Region \"%s\" iova=0x%"PRIx64"
> offset_within_region=0x%"PRIx64" qemu_real_host_page_mask=0x%"PRIxPTR ":
> cannot be mapped for DMA"
So here we've been passed qemu_real_host_page_size but we're again
printing "qemu_real_host_page_mask=0x%...". To make things slightly
more complicated, qemu_real_host_page_mask is now an intptr_t, which is
arbitrarily not supported in trace commands, while
qemu_real_host_page_size is a uintptr_t which is supported in trace
commands :-\ I'll let you decide how you want to resolve this. Thanks,
Alex
