From 11b41626bd5327332f5805ad8f8580365a363067 Mon Sep 17 00:00:00 2001 From: James Morse Date: Tue, 18 Jun 2019 16:18:09 +0100 Subject: KVM: arm64: Skip more of the SError vaxorcism During __guest_exit() we need to consume any SError left pending by the guest so it doesn't contaminate the host. With v8.2 we use the ESB-instruction. For systems without v8.2, we use dsb+isb and unmask SError. We do this on every guest exit. Use the same dsb+isr_el1 trick, this lets us know if an SError is pending after the dsb, allowing us to skip the isb and self-synchronising PSTATE write if its not. This means SError remains masked during KVM's world-switch, so any SError that occurs during this time is reported by the host, instead of causing a hyp-panic. As we're benchmarking this code lets polish the layout. If you give gcc likely()/unlikely() hints in an if() condition, it shuffles the generated assembly so that the likely case is immediately after the branch. Lets do the same here. Signed-off-by: James Morse Changes since v2: * Added isb after the dsb to prevent an early read Signed-off-by: Marc Zyngier --- arch/arm64/kvm/hyp/entry.S | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) (limited to 'arch') diff --git a/arch/arm64/kvm/hyp/entry.S b/arch/arm64/kvm/hyp/entry.S index 5e25cc0e6aab..e5cc8d66bf53 100644 --- a/arch/arm64/kvm/hyp/entry.S +++ b/arch/arm64/kvm/hyp/entry.S @@ -151,8 +151,16 @@ alternative_if ARM64_HAS_RAS_EXTN orr x0, x0, #(1<