From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pf1-f202.google.com (mail-pf1-f202.google.com [209.85.210.202]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id EF9823FDD for ; Tue, 1 Feb 2022 01:09:03 +0000 (UTC) Received: by mail-pf1-f202.google.com with SMTP id 68-20020a621547000000b004c74bbd2819so8234835pfv.18 for ; Mon, 31 Jan 2022 17:09:03 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=reply-to:date:in-reply-to:message-id:mime-version:references :subject:from:to:cc; bh=bL3FT8k/Xb3BcGI4WIfdGnBaIJMFJqmCvBuj1gJGH44=; b=qfjP1xUS1KlVS/IMykXefKvK1qQTncFnnytcKJMuNz7cZ6izT1HFdUafvswOgJug6w fUu2gRE/sPO/gMGaQJHy1cu/gikzlTFd+dwYsScIQ2aSEr19oNQfPZGlCSgrgT+A/ptb /BmWw9Q/5FLUgVtaJXFmF+ufSdVc0dVArOlkXmwriEDJ5vmsdUA1krlC7d3M4dgj/hAk ZH38ahZRKwAFuq+7rfQkwCiebPXcQlBJDlblbvkGBTV3eebX1oiryLzUoQsHW5mONR+9 1uIdR6azhY2x3J/pkEG8jDjFnokQdpdQEl+iLKEku7fanF+2DkTtHnGCKT2OvwN8+DmO kjOA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:reply-to:date:in-reply-to:message-id :mime-version:references:subject:from:to:cc; bh=bL3FT8k/Xb3BcGI4WIfdGnBaIJMFJqmCvBuj1gJGH44=; b=fjfzq3bFRqRvgVhQLoiYICnf1PzbRBMAqMOWREIlzfS1pj2IZ60U5+Sl/x7QMlOwfN dthdD9WUIGUu+PJJ8eVUcvGAlE9bmbpvx7cD/qVZiw0bLP9EvlOB93KJvMujbVo8kSrw tZv31jJ6QZtVbZ1uZS0YzO07KLdIo63M72rUS+pvm3WUgxGOu3TSAzR9nZ0zDmZdeI/H WB+cSq/mmf/QQZDjw+gj2eTqfY6fXcXdz6d42W8QehSxr5S4+bwH0G4kJZ5fwzL2UD9y uE5ojrojMI6JVwqkSfAn4q/m9ZTBumNcDtVa8fw6GQ5oKo6uUfaqNCowFFQFxrzT2ans Je8g== X-Gm-Message-State: AOAM5312GzIYitcl/eEyOw1pGzfayOEGypgpVbDz104lKJLuCzynwfiS vgyqJv33pGFTFtSq6hBo8ssQKQO+h0s= X-Google-Smtp-Source: ABdhPJyr1xQ8ILXqOSdU52v8l3fst3RJPIJ4yAP+ddUL0kFfLBBG3IGhmHWreArnTTL96e8JdujXax4R5iE= X-Received: from seanjc.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:3e5]) (user=seanjc job=sendgmr) by 2002:a17:902:7784:: with SMTP id o4mr23247435pll.173.1643677743484; Mon, 31 Jan 2022 17:09:03 -0800 (PST) Reply-To: Sean Christopherson Date: Tue, 1 Feb 2022 01:08:38 +0000 In-Reply-To: <20220201010838.1494405-1-seanjc@google.com> Message-Id: <20220201010838.1494405-6-seanjc@google.com> Precedence: bulk X-Mailing-List: llvm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20220201010838.1494405-1-seanjc@google.com> X-Mailer: git-send-email 2.35.0.rc2.247.g8bbb082509-goog Subject: [PATCH 5/5] KVM: x86: Bail to userspace if emulation of atomic user access faults From: Sean Christopherson To: Paolo Bonzini , Nathan Chancellor , Nick Desaulniers Cc: Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , kvm@vger.kernel.org, llvm@lists.linux.dev, linux-kernel@vger.kernel.org, Peter Zijlstra , syzbot+6cde2282daa792c49ab8@syzkaller.appspotmail.com Content-Type: text/plain; charset="UTF-8" Exit to userspace when emulating an atomic guest access if the CMPXCHG on the userspace address faults. Emulating the access as a write and thus likely treating it as emulated MMIO is wrong, as KVM has already confirmed there is a valid, writable memslot. Signed-off-by: Sean Christopherson --- arch/x86/kvm/x86.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 37064d565bbc..66c5410dd4c3 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -7217,7 +7217,7 @@ static int emulator_cmpxchg_emulated(struct x86_emulate_ctxt *ctxt, } if (r < 0) - goto emul_write; + return X86EMUL_UNHANDLEABLE; if (r) return X86EMUL_CMPXCHG_FAILED; -- 2.35.0.rc2.247.g8bbb082509-goog