Re: [PATCH v2 04/37] powerpc/64s: remove KVM SKIP test from instruction breakpoint handler
flat view
From: Daniel Axtens <hidden>
Date: 2021-02-26 05:45:24
Nicholas Piggin [off-list ref] 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 <redacted> Kind regards, Daniel
quoted hunk ↗ jump to hunk
Reviewed-by: Fabiano Rosas <redacted> Signed-off-by: Nicholas Piggin <npiggin@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