On 08/04/2025 10:31 am, Roger Pau Monne wrote:
> When running on AMD hardware in HVM mode the guest linear address (GLA)
> will not be provided to hvm_emulate_one_mmio(), and instead is
> unconditionally set of ~0. As a consequence mmio_ro_emulated_write() will
> always report an error, as the fault GLA generated by the emulation of the
> access won't be ~0.
>
> Fix this by only checking for the fault GLA in mmio_ro_emulated_write()
> when the guest is PV.
>
> Fixes: 33c19df9a5a0 ('x86/PCI: intercept accesses to RO MMIO from dom0s in
> HVM containers')
> Signed-off-by: Roger Pau Monné <roger....@citrix.com>
I think there are several bugs here.
We do get %cr2 reliably for PV and Shadow guests.
Intel EPT may or may not give us GLA. e.g. writes for pagetable A/D
updates don't get GLA.
Defaulting to ~0 isn't ok. We need some kind of GLA-valid signal,
except for HAP guests, it isn't even the GLA we care about, it's the GPA
which identifies the MMIO region.
We shouldn't terminate the emulation if there's no GLA to check. In the
case that we don't have a GLA, we should translate the memory operand
and cross-check the GPA. We'll definitely have one of the two to hand.
~Andrew
