KVM: arm64: nv: Don't advance PC when pending an SVE exception

Jan reports that running a nested guest on Neoverse-V2 leads to a WARN
in the host due to simultaneously pending an exception and PC increment
after an access to ZCR_EL2.

Returning true from a sysreg accessor is an indication that the sysreg
instruction has been retired. Of course this isn't the case when we've
pended a synchronous SVE exception for the guest. Fix the return value
and let the exception propagate to the guest as usual.

Reported-by: Jan Kotas <jank@cadence.com>
Closes: https://lore.kernel.org/kvmarm/865xd61tt5.wl-maz@kernel.org/
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
Signed-off-by: Marc Zyngier <maz@kernel.org>

diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 4a75e5f0c259df04cee5e958d88921af8d90861b..ee8a7033c85bfcad71c2698f9331acb99b22fdc4 100644 (file)
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -2704,7 +2704,7 @@ static bool access_zcr_el2(struct kvm_vcpu *vcpu,
 
        if (guest_hyp_sve_traps_enabled(vcpu)) {
                kvm_inject_nested_sve_trap(vcpu);
-               return true;
+               return false;
        }
 
        if (!p->is_write) {