[PATCH v1 2/6] KVM: arm64: Set FnV for VCPU when FAR_EL2 is invalid

[Jiaqi Yan]

Certain microarchitectures (e.g. Neoverse V2) do not keep track of
the faulting address for a memory load that consumes poisoned data
and results in a synchronous external abort (SEA). This means the
faulting guest physical address is unavailable when KVM handles such
SEA in EL2, and FAR_EL2 just holds a garbage value.

In case VMM later asks KVM to synchronously inject a SEA into the
guest, KVM should set FnV bit
- in VCPU's ESR_EL1 to let guest kernel know that FAR_EL1 is invalid
  and holds garbage value
- in VCPU's ESR_EL2 to let nested virtualization know that FAR_EL2
  is invalid and holds garbage value

Signed-off-by: Jiaqi Yan <jiaqiyan at google.com>
---
 arch/arm64/kvm/inject_fault.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/arm64/kvm/inject_fault.c b/arch/arm64/kvm/inject_fault.c
index a640e839848e6..b4f9a09952ead 100644
--- a/arch/arm64/kvm/inject_fault.c
+++ b/arch/arm64/kvm/inject_fault.c
@@ -81,6 +81,9 @@ static void inject_abt64(struct kvm_vcpu *vcpu, bool is_iabt, unsigned long addr
 	if (!is_iabt)
 		esr |= ESR_ELx_EC_DABT_LOW << ESR_ELx_EC_SHIFT;
 
+	if (!kvm_vcpu_sea_far_valid(vcpu))
+		esr |= ESR_ELx_FnV;
+
 	esr |= ESR_ELx_FSC_EXTABT;
 
 	if (match_target_el(vcpu, unpack_vcpu_flag(EXCEPT_AA64_EL1_SYNC))) {
-- 
2.49.0.967.g6a0df3ecc3-goog