Re: [PATCH v4 18/21] KVM: arm64: Handle RAS SErrors from EL1 on guest exit

Christoffer Dall
2017-10-31T05:55:17Z

On Thu, Oct 19, 2017 at 03:58:04PM +0100, James Morse wrote:
> We expect to have firmware-first handling of RAS SErrors, with errors
> notified via an APEI method. For systems without firmware-first, add
> some minimal handling to KVM.
>
> There are two ways KVM can take an SError due to a guest, either may be a
> RAS error: we exit the guest due to an SError routed to EL2 by HCR_EL2.AMO,
> or we take an SError from EL2 when we unmask PSTATE.A from __guest_exit.
>
> For SError that interrupt a guest and are routed to EL2 the existing
> behaviour is to inject an impdef SError into the guest.
>
> Add code to handle RAS SError based on the ESR. For uncontained errors
> arm64_is_blocking_ras_serror() will panic(), these errors compromise
> the host too. All other error types are contained: For the 'blocking'
> errors the vCPU can't make progress, so we inject a virtual SError.
> We ignore contained errors where we can make progress as if we're lucky,
> we may not hit them again.
>
> Signed-off-by: James Morse <james.morse@arm.com>

Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>

> ---
> arch/arm64/kvm/handle_exit.c | 9 ++++++++-
> 1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.c
> index 7debb74843a0..345fdbba6c2e 100644
> --- a/arch/arm64/kvm/handle_exit.c
> +++ b/arch/arm64/kvm/handle_exit.c
> @@ -28,12 +28,19 @@
> #include <asm/kvm_emulate.h>
> #include <asm/kvm_mmu.h>
> #include <asm/kvm_psci.h>
> +#include <asm/traps.h>
>
> #define CREATE_TRACE_POINTS
> #include "trace.h"
>
> typedef int (*exit_handle_fn)(struct kvm_vcpu *, struct kvm_run *);
>
> +static void kvm_handle_guest_serror(struct kvm_vcpu *vcpu, u32 esr)
> +{
> + if (!arm64_is_ras_serror(esr) || arm64_blocking_ras_serror(NULL, esr))
> + kvm_inject_vabt(vcpu);
> +}
> +
> static int handle_hvc(struct kvm_vcpu *vcpu, struct kvm_run *run)
> {
> int ret;
> @@ -211,7 +218,7 @@ int handle_exit(struct kvm_vcpu *vcpu, struct kvm_run *run,
> case ARM_EXCEPTION_IRQ:
> return 1;
> case ARM_EXCEPTION_EL1_SERROR:
> - kvm_inject_vabt(vcpu);
> + kvm_handle_guest_serror(vcpu, kvm_vcpu_get_hsr(vcpu));
> return 1;
> case ARM_EXCEPTION_TRAP:
> /*
> --
> 2.13.3
>