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KVM: arm64: nv: Honor SError exception routing / masking

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To date KVM has used HCR_EL2.VSE to track the state of a pending SError
for the guest. With this bit set, hardware respects the EL1 exception
routing / masking rules and injects the vSError when appropriate.

This isn't correct for NV guests as hardware is oblivious to vEL2's
intentions for SErrors. Better yet, with FEAT_NV2 the guest can change
the routing behind our back as HCR_EL2 is redirected to memory. Cope
with this mess by:

 - Using a flag (instead of HCR_EL2.VSE) to track the pending SError
   state when SErrors are unconditionally masked for the current context

 - Resampling the routing / masking of a pending SError on every guest
   entry/exit

 - Emulating exception entry when SError routing implies a translation
   regime change

Reviewed-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20250708172532.1699409-7-oliver.upton@linux.dev
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
This commit is contained in:
Oliver Upton
2025-07-08 10:25:11 -07:00
parent 9aba641b9e
commit 77ee70a073
11 changed files with 144 additions and 38 deletions
Download Patch File Download Diff File Expand all files Collapse all files

14
arch/arm64/kvm/emulate-nested.c
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@@ -2714,6 +2714,9 @@ static void kvm_inject_el2_exception(struct kvm_vcpu *vcpu, u64 esr_el2,
case except_type_irq:
kvm_pend_exception(vcpu, EXCEPT_AA64_EL2_IRQ);
break;
case except_type_serror:
kvm_pend_exception(vcpu, EXCEPT_AA64_EL2_SERR);
break;
default:
WARN_ONCE(1, "Unsupported EL2 exception injection %d\n", type);
}
@@ -2821,3 +2824,14 @@ int kvm_inject_nested_sea(struct kvm_vcpu *vcpu, bool iabt, u64 addr)
vcpu_write_sys_reg(vcpu, FAR_EL2, addr);
return kvm_inject_nested_sync(vcpu, esr);
}
int kvm_inject_nested_serror(struct kvm_vcpu *vcpu, u64 esr)
{
/*
* Hardware sets up the EC field when propagating ESR as a result of
* vSError injection. Manually populate EC for an emulated SError
* exception.
*/
esr |= FIELD_PREP(ESR_ELx_EC_MASK, ESR_ELx_EC_SERROR);
return kvm_inject_nested(vcpu, esr, except_type_serror);
}