On Thu, 19 Aug 2021 23:34:06 +0100,
Raghavendra Rao Ananta <rananta@xxxxxxxxxx> wrote:
>
> Potentially, the guests could trigger a debug exception that's
> outside the exception class range.
How? All the exception classes that lead to this functions are already
handled in the switch/case statement.
> This could lead to an excessive syslog flooding. Hence, ratelimit
> the error message.
>
> Signed-off-by: Raghavendra Rao Ananta <rananta@xxxxxxxxxx>
> ---
> arch/arm64/kvm/handle_exit.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.c
> index 04ebab299aa4..c7cec7ffe93c 100644
> --- a/arch/arm64/kvm/handle_exit.c
> +++ b/arch/arm64/kvm/handle_exit.c
> @@ -134,7 +134,7 @@ static int kvm_handle_guest_debug(struct kvm_vcpu *vcpu)
> case ESR_ELx_EC_BRK64:
> break;
> default:
> - kvm_err("%s: un-handled case esr: %#08x\n",
> + kvm_pr_unimpl("%s: un-handled case esr: %#08x\n",
> __func__, (unsigned int) esr);
> ret = -1;
> break;
My take on this is that this code isn't reachable, and that it could
be better rewritten as:
diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.c
index 6f48336b1d86..ae7ec086827b 100644
--- a/arch/arm64/kvm/handle_exit.c
+++ b/arch/arm64/kvm/handle_exit.c
@@ -119,28 +119,14 @@ static int kvm_handle_guest_debug(struct kvm_vcpu *vcpu)
{
struct kvm_run *run = vcpu->run;
u32 esr = kvm_vcpu_get_esr(vcpu);
- int ret = 0;
run->exit_reason = KVM_EXIT_DEBUG;
run->debug.arch.hsr = esr;
- switch (ESR_ELx_EC(esr)) {
- case ESR_ELx_EC_WATCHPT_LOW:
+ if (ESR_ELx_EC(esr) == ESR_ELx_EC_WATCHPT_LOW)
run->debug.arch.far = vcpu->arch.fault.far_el2;
- fallthrough;
- case ESR_ELx_EC_SOFTSTP_LOW:
- case ESR_ELx_EC_BREAKPT_LOW:
- case ESR_ELx_EC_BKPT32:
- case ESR_ELx_EC_BRK64:
- break;
- default:
- kvm_err("%s: un-handled case esr: %#08x\n",
- __func__, (unsigned int) esr);
- ret = -1;
- break;
- }
- return ret;
+ return 0;
}
static int kvm_handle_unknown_ec(struct kvm_vcpu *vcpu)
Thanks,
M.
--
Without deviation from the norm, progress is not possible.
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