[PATCH] KVM: arm64: nv: Drop bogus WARN for write to ZCR_EL2

[PATCH] KVM: arm64: nv: Drop bogus WARN for write to ZCR_EL2

[Oliver Upton]

It is entirely possible for a guest to write to the ZCR_EL2 sysreg alias
while in a nested context, as it is expected if FEAT_NV2 is advertised
to the L1 hypervisor.

Get rid of the bogus WARN which, since the hyp vectors were installed at
this point, has the effect of a hyp_panic...

Cc: stable@vger.kernel.org
Fixes: 0cfc85b8f5cf ("KVM: arm64: nv: Load guest FP state for ZCR_EL2 trap")
Signed-off-by: Oliver Upton <oupton@kernel.org>
---
 arch/arm64/kvm/hyp/include/hyp/switch.h | 2 --
 1 file changed, 2 deletions(-)

diff --git a/arch/arm64/kvm/hyp/include/hyp/switch.h b/arch/arm64/kvm/hyp/include/hyp/switch.h
index 161bb2a3e1d9..2e96ac3b08c0 100644
--- a/arch/arm64/kvm/hyp/include/hyp/switch.h
+++ b/arch/arm64/kvm/hyp/include/hyp/switch.h
@@ -595,8 +595,6 @@ static inline bool kvm_hyp_handle_fpsimd(struct kvm_vcpu *vcpu, u64 *exit_code)
 			return false;
 		break;
 	case ESR_ELx_EC_SYS64:
-		if (WARN_ON_ONCE(!is_hyp_ctxt(vcpu)))
-			return false;
 		fallthrough;
 	case ESR_ELx_EC_SVE:
 		if (!sve_guest)

base-commit: 1ee27dacbe5dc4def481794d899d67b0d4570094
-- 
2.47.3

Re: [PATCH] KVM: arm64: nv: Drop bogus WARN for write to ZCR_EL2

[Marc Zyngier]

On Sun, 14 Jun 2026 22:13:24 -0700, Oliver Upton wrote:
> It is entirely possible for a guest to write to the ZCR_EL2 sysreg alias
> while in a nested context, as it is expected if FEAT_NV2 is advertised
> to the L1 hypervisor.
> 
> Get rid of the bogus WARN which, since the hyp vectors were installed at
> this point, has the effect of a hyp_panic...
> 
> [...]

Applied to fixes, thanks!

[1/1] KVM: arm64: nv: Drop bogus WARN for write to ZCR_EL2
      commit: 9f1667098c6ae7ec81a9a56859cfdacb822aa0d0

Cheers,

	M.
-- 
Without deviation from the norm, progress is not possible.