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Fri, 27 Nov 2020 08:50:02 +0000 MIME-Version: 1.0 Date: Fri, 27 Nov 2020 08:50:02 +0000 From: Marc Zyngier To: Alexandru Elisei Subject: Re: [PATCH 5/8] KVM: arm64: Remove PMU RAZ/WI handling In-Reply-To: References: <20201113182602.471776-1-maz@kernel.org> <20201113182602.471776-6-maz@kernel.org> User-Agent: Roundcube Webmail/1.4.9 Message-ID: <7ae93087a57bd5f6a348f0d4d6a7db2d@kernel.org> X-Sender: maz@kernel.org X-SA-Exim-Connect-IP: 51.254.78.96 X-SA-Exim-Rcpt-To: alexandru.elisei@arm.com, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, kernel-team@android.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201127_035006_249579_C6B09D11 X-CRM114-Status: GOOD ( 16.10 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kernel-team@android.com, kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org, kvm@vger.kernel.org Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 2020-11-26 15:06, Alexandru Elisei wrote: > Hi Marc, > > This patch looks correct to me, I checked in the Arm ARM DDI 0487F.b > and indeed > all accesses to the PMU registers are UNDEFINED if the PMU is not > present. > > I checked all the accessors and now all the PMU registers that KVM > emulates will > inject an undefined exception if the VCPU feature isn't set. There's > one register > that we don't emulate, PMMIR_EL1, I suppose that's because it's part of > PMU > ARMv8.4 and KVM advertises ARMv8.1; if the guest tries to access it, it > will get > an undefined exception and KVM will print a warning in > emulate_sys_reg(). Funny that. I wrote a patch for that a long while ago, and obviously never did anything with it [1]... Actually, the whole series was silently dropped. I guess I had other things to think about at the time! Let me pick that up again. > Reviewed-by: Alexandru Elisei Thanks! M. [1] https://lore.kernel.org/kvmarm/20200216185324.32596-6-maz@kernel.org/ -- Jazz is not dead. It just smells funny... _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel