On 5/22/24 18:59, 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>
I forgot to pick up Julien's ack [0]. [0] https://lore.kernel.org/xen-devel/8fa02e06-d8dc-4e73-a58e-e4d84b090...@xen.org/ > --- > v14->v15: > * re-order so this patch comes before ("xen/arm: translate virtual PCI > bus topology for guests") > * s/access_mask/invalid/ > * add U suffix to 1 > * s/uint8_t/unsigned int/ > * s/uint64_t/register_t/ > * although Julien gave an Acked-by on v14, I omitted it due to the > changes made in v15 > > v9->10: > * New patch in v10. > --- > xen/arch/arm/vpci.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/xen/arch/arm/vpci.c b/xen/arch/arm/vpci.c > index 3bc4bb55082a..b63a356bb4a8 100644 > --- a/xen/arch/arm/vpci.c > +++ b/xen/arch/arm/vpci.c > @@ -29,6 +29,8 @@ static int vpci_mmio_read(struct vcpu *v, mmio_info_t *info, > { > struct pci_host_bridge *bridge = p; > pci_sbdf_t sbdf = vpci_sbdf_from_gpa(bridge, info->gpa); > + const unsigned int access_size = (1U << info->dabt.size) * 8; > + const register_t invalid = GENMASK_ULL(access_size - 1, 0); > /* data is needed to prevent a pointer cast on 32bit */ > unsigned long data; > > @@ -39,7 +41,7 @@ static int vpci_mmio_read(struct vcpu *v, mmio_info_t *info, > return 1; > } > > - *r = ~0ul; > + *r = invalid; > > return 0; > }
