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spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Type: Content-Transfer-Encoding:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:Message-ID:References:In-Reply-To:Subject:To:From: Date:MIME-Version:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=Oj7bTguTJRPb/S8kkchQghIqvMXVsi0GL6FEw2X1aaQ=; b=kCcIr4ZOYPRn5nsb2Ff1gwQoh EG1ihxg2gFu4CYX7bwbHo6VW9wm/JrgKaMZriG9cCkCFWtwlA2HPIc7nrYCwcw7Ddlh8TJ+TkZ7Ce WfKX0LB6dRy2/5QmSyOWDgDASDLo4Zvey4OfoylCMwy+7L4KkP51TDQ1wqv634SM4N6aNUCEF1+JR SpMwstfi27weAQFNdLek5HEIXMe5hCq8P0h8kUD+COKkCVocZHiFB41pQE7DeaKyIhY7vQ/OJwZEZ MxodcybHJ5TJUe3689a7bHU7I+K2LcByYeDoz3yZXpfuVOIvlGLMWbbNGa8YZONoGQnLgBHPWnnq6 Qwe3AAU+w==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1lFhxt-00046F-0D; Fri, 26 Feb 2021 18:35:49 +0000 Received: from mail.kernel.org ([198.145.29.99]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1lFhxq-00045H-8L for linux-arm-kernel@lists.infradead.org; Fri, 26 Feb 2021 18:35:47 +0000 Received: from disco-boy.misterjones.org (disco-boy.misterjones.org [51.254.78.96]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 5692A601FC; Fri, 26 Feb 2021 18:35:44 +0000 (UTC) Received: from disco-boy.misterjones.org ([51.254.78.96] helo=www.loen.fr) by disco-boy.misterjones.org with esmtpsa (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (Exim 4.94) (envelope-from ) id 1lFhxm-00G5ts-9K; Fri, 26 Feb 2021 18:35:42 +0000 MIME-Version: 1.0 Date: Fri, 26 Feb 2021 18:35:42 +0000 From: Marc Zyngier To: Will Deacon Subject: Re: [PATCH] KVM: arm64: Avoid corrupting vCPU context register in guest exit In-Reply-To: <20210226181211.14542-1-will@kernel.org> References: <20210226181211.14542-1-will@kernel.org> User-Agent: Roundcube Webmail/1.4.11 Message-ID: X-Sender: maz@kernel.org X-SA-Exim-Connect-IP: 51.254.78.96 X-SA-Exim-Rcpt-To: will@kernel.org, kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org, kernel-team@android.com, ascull@google.com, stable@vger.kernel.org, qperret@google.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-20210226_133546_400594_388AE51A X-CRM114-Status: GOOD ( 18.97 ) 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: Quentin Perret , stable@vger.kernel.org, Andrew Scull , kernel-team@android.com, kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.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 2021-02-26 18:12, Will Deacon wrote: > Commit 7db21530479f ("KVM: arm64: Restore hyp when panicking in guest > context") tracks the currently running vCPU, clearing the pointer to > NULL on exit from a guest. > > Unfortunately, the use of 'set_loaded_vcpu' clobbers x1 to point at the > kvm_hyp_ctxt instead of the vCPU context, causing the subsequent RAS > code to go off into the weeds when it saves the DISR assuming that the > CPU context is embedded in a struct vCPU. > > Leave x1 alone and use x3 as a temporary register instead when clearing > the vCPU on the guest exit path. > > Cc: Marc Zyngier > Cc: Andrew Scull > Cc: > Fixes: 7db21530479f ("KVM: arm64: Restore hyp when panicking in guest > context") > Suggested-by: Quentin Perret > Signed-off-by: Will Deacon > --- > > This was pretty awful to debug! > > arch/arm64/kvm/hyp/entry.S | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/arm64/kvm/hyp/entry.S b/arch/arm64/kvm/hyp/entry.S > index b0afad7a99c6..0c66a1d408fd 100644 > --- a/arch/arm64/kvm/hyp/entry.S > +++ b/arch/arm64/kvm/hyp/entry.S > @@ -146,7 +146,7 @@ SYM_INNER_LABEL(__guest_exit, SYM_L_GLOBAL) > // Now restore the hyp regs > restore_callee_saved_regs x2 > > - set_loaded_vcpu xzr, x1, x2 > + set_loaded_vcpu xzr, x2, x3 > > alternative_if ARM64_HAS_RAS_EXTN > // If we have the RAS extensions we can consume a pending error Grmbl... How comes we have never seen that for the past 5 months, including on CPUs that implement RAS? Thanks, M. -- 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