From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nicholas Piggin Date: Thu, 01 Apr 2021 09:47:49 +0000 Subject: Re: [PATCH v4 09/46] powerpc/64s: remove KVM SKIP test from instruction breakpoint handler Message-Id: <1617270447.zkb024siva.astroid@bobo.none> List-Id: References: <20210323010305.1045293-1-npiggin@gmail.com> <20210323010305.1045293-10-npiggin@gmail.com> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Paul Mackerras Cc: Fabiano Rosas , linuxppc-dev@lists.ozlabs.org, kvm-ppc@vger.kernel.org, Daniel Axtens Excerpts from Paul Mackerras's message of March 31, 2021 2:54 pm: > On Tue, Mar 23, 2021 at 11:02:28AM +1000, Nicholas Piggin wrote: >> 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). >> >> Reviewed-by: Daniel Axtens >> Reviewed-by: Fabiano Rosas >> Signed-off-by: Nicholas Piggin > > It might be worth noting in the commit message that the 0x1300 > interrupt was dropped from the architecture a long time ago and is not > generated by P7, P8, P9 or P10. Good background, I'll add that. Thanks, Nick > > Acked-by: Paul Mackerras >