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Fri, 04 Oct 2024 08:41:03 -0700 (PDT) Received: from [192.168.1.183] ([89.47.253.130]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-42f89e89b42sm583875e9.13.2024.10.04.08.41.02 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 04 Oct 2024 08:41:02 -0700 (PDT) Message-ID: Date: Fri, 4 Oct 2024 16:41:10 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [bug report] KVM: arm64: BUG when reading kcore with kvm-arm.mode=protected To: Oliver Upton Cc: kvmarm@lists.linux.dev, "linux-arm-kernel@lists.infradead.org" , will@kernel.org, tabba@google.com, maz@kernel.org References: Content-Language: en-US From: James Clark In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20241004_084105_285385_84FD9884 X-CRM114-Status: GOOD ( 14.11 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 02/10/2024 16:44, Oliver Upton wrote: > +cc relevant folks > > Hi James, > > On Wed, Oct 02, 2024 at 02:23:32PM +0100, James Clark wrote: >> Hi, >> >> I noticed this when running the Perf tests so I'm reporting it here (I don't >> actually need kcore FWIW). I tested from 6.1 to 6.11 with the same results: > > Yeah, this is (somewhat) intended behavior. By reading kcore you wind up > reading from memory that isn't in a visible state for the host (e.g. hyp > text). > > Protected mode is very much a WIP, and is expected to be rough around the > edges like this. Eventually the hypervisor will inject an abort into the > host for disallowed memory accesses instead of tripping a BUG_ON(). We > don't have that upstream right now. > Thanks for the confirmation. I assumed as much but just wanted to be sure.