[PATCH v2 04/37] powerpc/64s: remove KVM SKIP test from instruction breakpoint handler
Daniel Axtens
dja at axtens.net
Fri Feb 26 16:44:39 AEDT 2021
Nicholas Piggin <npiggin at gmail.com> writes:
> The code being executed in KVM_GUEST_MODE_SKIP is hypervisor code with
> MSR[IR]=0, so the faults of concern are the d-side ones caused by access
> to guest context by the hypervisor.
>
> Instruction breakpoint interrupts are not a concern here. It's unlikely
> any good would come of causing breaks in this code, but skipping the
> instruction that caused it won't help matters (e.g., skip the mtmsr that
> sets MSR[DR]=0 or clears KVM_GUEST_MODE_SKIP).
I'm not entirely clear on the example here, but the patch makes sense
and I can follow your logic for removing the IKVM_SKIP handler from the
instruction breakpoint exception.
On that basis:
Reviewed-by: Daniel Axtens <dja at axtens.net>
Kind regards,
Daniel
>
> Reviewed-by: Fabiano Rosas <farosas at linux.ibm.com>
> Signed-off-by: Nicholas Piggin <npiggin at gmail.com>
> ---
> arch/powerpc/kernel/exceptions-64s.S | 1 -
> 1 file changed, 1 deletion(-)
>
> diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
> index a027600beeb1..0097e0676ed7 100644
> --- a/arch/powerpc/kernel/exceptions-64s.S
> +++ b/arch/powerpc/kernel/exceptions-64s.S
> @@ -2553,7 +2553,6 @@ EXC_VIRT_NONE(0x5200, 0x100)
> INT_DEFINE_BEGIN(instruction_breakpoint)
> IVEC=0x1300
> #ifdef CONFIG_KVM_BOOK3S_PR_POSSIBLE
> - IKVM_SKIP=1
> IKVM_REAL=1
> #endif
> INT_DEFINE_END(instruction_breakpoint)
> --
> 2.23.0
More information about the Linuxppc-dev
mailing list