Nicholas Piggin <npiggin@xxxxxxxxx> writes:
> A number of machine check exceptions are triggerable by the guest.
> Ratelimit these to avoid a guest flooding the host console and logs.
>
> Signed-off-by: Nicholas Piggin <npiggin@xxxxxxxxx>
> ---
> arch/powerpc/kvm/book3s_hv.c | 11 ++++++++---
> 1 file changed, 8 insertions(+), 3 deletions(-)
>
> diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
> index e3b1839fc251..c94f9595133d 100644
> --- a/arch/powerpc/kvm/book3s_hv.c
> +++ b/arch/powerpc/kvm/book3s_hv.c
> @@ -1328,8 +1328,12 @@ static int kvmppc_handle_exit_hv(struct kvm_vcpu *vcpu,
> r = RESUME_GUEST;
> break;
> case BOOK3S_INTERRUPT_MACHINE_CHECK:
> - /* Print the MCE event to host console. */
> - machine_check_print_event_info(&vcpu->arch.mce_evt, false, true);
> + /*
> + * Print the MCE event to host console. Ratelimit so the guest
> + * can't flood the host log.
> + */
> + if (printk_ratelimit())
> + machine_check_print_event_info(&vcpu->arch.mce_evt,false, true);
You're not supposed to use printk_ratelimit(), because there's a single
rate limit state for all printks. ie. some other noisty printk() can
cause this one to never be printed.
I folded this in:
diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index cbbc4f0a26fe..cfaa91b27112 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -1327,12 +1327,14 @@ static int kvmppc_handle_exit_hv(struct kvm_vcpu *vcpu,
case BOOK3S_INTERRUPT_SYSTEM_RESET:
r = RESUME_GUEST;
break;
- case BOOK3S_INTERRUPT_MACHINE_CHECK:
+ case BOOK3S_INTERRUPT_MACHINE_CHECK: {
+ static DEFINE_RATELIMIT_STATE(rs, DEFAULT_RATELIMIT_INTERVAL,
+ DEFAULT_RATELIMIT_BURST);
/*
* Print the MCE event to host console. Ratelimit so the guest
* can't flood the host log.
*/
- if (printk_ratelimit())
+ if (__ratelimit(&rs))
machine_check_print_event_info(&vcpu->arch.mce_evt,false, true);
/*
@@ -1361,6 +1363,7 @@ static int kvmppc_handle_exit_hv(struct kvm_vcpu *vcpu,
r = RESUME_HOST;
break;
+ }
case BOOK3S_INTERRUPT_PROGRAM:
{
ulong flags;
@@ -1520,12 +1523,16 @@ static int kvmppc_handle_nested_exit(struct kvm_vcpu *vcpu)
r = RESUME_GUEST;
break;
case BOOK3S_INTERRUPT_MACHINE_CHECK:
+ {
+ static DEFINE_RATELIMIT_STATE(rs, DEFAULT_RATELIMIT_INTERVAL,
+ DEFAULT_RATELIMIT_BURST);
/* Pass the machine check to the L1 guest */
r = RESUME_HOST;
/* Print the MCE event to host console. */
- if (printk_ratelimit())
+ if (__ratelimit(&rs))
machine_check_print_event_info(&vcpu->arch.mce_evt, false, true);
break;
+ }
/*
* We get these next two if the guest accesses a page which it thinks
* it has mapped but which is not actually present, either because
cheers
