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hypervisor: mshv: Validate GPA mapping with GvaGpaValid flag

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The GvaGpaValid flag in the intercept message indicates whether
the provided GPA corresponds to the decoded GVA. Without checking
this flag, the emulator may incorrectly use a stale GPA mapping
when the hypervisor invalidates it.

Add a check for the GvaGpaValid flag before using the cached
(GVA, GPA) mapping. If the flag is clear, use a sentinel value
to force translate() to perform a proper hypercall-based
translation instead of using an invalid cached mapping.

Signed-off-by: Pedro Barbuda <pbarbuda@microsoft.com>
Signed-off-by: Muminul Islam <muislam@microsoft.com>
This commit is contained in:
Muminul Islam
2026-04-24 14:49:33 -07:00
committed by Wei Liu
parent 326cd88074
commit 842d02fdd9
2 changed files with 25 additions and 3 deletions
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21
hypervisor/src/mshv/mod.rs
View File

@@ -720,11 +720,28 @@ impl cpu::Vcpu for MshvVcpu {
let gva = info.guest_virtual_address;
let gpa = info.guest_physical_address;
debug!("Exit ({msg_type:?}) GVA {gva:x} GPA {gpa:x}");
// The GvaGpaValid flag indicates that the GPA in the intercept
// message corresponds to the GVA in the message. If that flag
// is set, and the GVA in the message matches the GVA in the decoded
// instruction, then the emulator can use the GPA provided by
// the hypervisor. Otherwise, the emulator must translate the GVA
// via a hypercall.
// SAFETY: accessing the bitfield union variant.
let gva_gpa_valid =
unsafe { info.memory_access_info.__bindgen_anon_1.gva_gpa_valid() != 0 };
debug!(
"Exit ({msg_type:?}) GVA {gva:x} GPA {gpa:x} \
gva_gpa_valid={gva_gpa_valid}"
);
let mut context = MshvEmulatorContext {
vcpu: self,
map: (gva, gpa),
map: if gva_gpa_valid {
(gva, gpa)
} else {
(u64::MAX, 0)
},
};
let old_state = context

7
hypervisor/src/mshv/x86_64/emulator.rs
View File

@@ -19,7 +19,12 @@ pub struct MshvEmulatorContext<'a> {
}
impl MshvEmulatorContext<'_> {
// Do the actual gva -> gpa translation
// Do the actual gva -> gpa translation.
//
// When the hypervisor sets GvaGpaValid in the intercept message, `map`
// caches the (gva, gpa) pair as a fast path that avoids a translate
// hypercall. When the flag is clear, `map` is set to a sentinel
// (u64::MAX, 0) so this shortcut never fires.
#[allow(non_upper_case_globals)]
fn translate(&self, gva: u64, flags: u32) -> Result<u64, PlatformError> {
if self.map.0 == gva {