From mboxrd@z Thu Jan 1 00:00:00 1970 From: Fabiano Rosas Date: Mon, 22 Feb 2021 22:22:51 +0000 Subject: Re: [PATCH 02/13] powerpc/64s: remove KVM SKIP test from instruction breakpoint handler Message-Id: <87k0qzyc78.fsf@linux.ibm.com> List-Id: References: <20210219063542.1425130-1-npiggin@gmail.com> <20210219063542.1425130-3-npiggin@gmail.com> In-Reply-To: <20210219063542.1425130-3-npiggin@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Nicholas Piggin , kvm-ppc@vger.kernel.org Cc: linuxppc-dev@lists.ozlabs.org, Nicholas Piggin Nicholas Piggin 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). > > Signed-off-by: Nicholas Piggin Reviewed-by: Fabiano Rosas > --- > 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 5d0ad3b38e90..5bc689a546ae 100644 > --- a/arch/powerpc/kernel/exceptions-64s.S > +++ b/arch/powerpc/kernel/exceptions-64s.S > @@ -2597,7 +2597,6 @@ 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)