Hi Stewart,
On 14/05/2024 15:33, Stewart Hildebrand wrote:
From: Volodymyr Babchuk <volodymyr_babc...@epam.com>
Guest can try to read config space using different access sizes: 8,
16, 32, 64 bits. We need to take this into account when we are
returning an error back to MMIO handler, otherwise it is possible to
provide more data than requested: i.e. guest issues LDRB instruction
to read one byte, but we are writing 0xFFFFFFFFFFFFFFFF in the target
register.
Signed-off-by: Volodymyr Babchuk <volodymyr_babc...@epam.com>
Signed-off-by: Stewart Hildebrand <stewart.hildebr...@amd.com>
With one remark below:
Acked-by: Julien Grall <jgr...@amazon.com>
---
v9->10:
* New patch in v10.
---
xen/arch/arm/vpci.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/xen/arch/arm/vpci.c b/xen/arch/arm/vpci.c
index 348ba0fbc860..aaf9d9120c3d 100644
--- a/xen/arch/arm/vpci.c
+++ b/xen/arch/arm/vpci.c
@@ -41,6 +41,8 @@ static int vpci_mmio_read(struct vcpu *v, mmio_info_t *info,
{
struct pci_host_bridge *bridge = p;
pci_sbdf_t sbdf;
+ const uint8_t access_size = (1 << info->dabt.size) * 8;
+ const uint64_t access_mask = GENMASK_ULL(access_size - 1, 0);
/* data is needed to prevent a pointer cast on 32bit */
unsigned long data;
@@ -48,7 +50,7 @@ static int vpci_mmio_read(struct vcpu *v, mmio_info_t *info,
if ( !vpci_sbdf_from_gpa(v->domain, bridge, info->gpa, &sbdf) )
{
- *r = ~0UL;
+ *r = access_mask;
The name 'access_mask' is a bit confusing. I would not expect such value
for be returned to the guest. What about 'invalid'?
Also can you confirm whether patches #4 and #5 be committed without the
rest of the series?
Cheers,
--
Julien Grall
