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Mon, 17 May 2021 17:42:54 +0000 From: Tom Lendacky To: linux-kernel@vger.kernel.org, x86@kernel.org Cc: Thomas Gleixner , Ingo Molnar , Borislav Petkov , Joerg Roedel , Paolo Bonzini , Jim Mattson , Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Brijesh Singh , stable@vger.kernel.org Subject: [PATCH v2 2/2] x86/sev-es: Invalidate the GHCB after completing VMGEXIT Date: Mon, 17 May 2021 12:42:33 -0500 Message-Id: <5a8130462e4f0057ee1184509cd056eedd78742b.1621273353.git.thomas.lendacky@amd.com> X-Mailer: git-send-email 2.31.0 In-Reply-To: <8c07662ec17d3d82e5c53841a1d9e766d3bdbab6.1621273353.git.thomas.lendacky@amd.com> References: <8c07662ec17d3d82e5c53841a1d9e766d3bdbab6.1621273353.git.thomas.lendacky@amd.com> X-Originating-IP: [165.204.77.1] X-ClientProxiedBy: SN6PR16CA0059.namprd16.prod.outlook.com (2603:10b6:805:ca::36) To DM5PR12MB1355.namprd12.prod.outlook.com (2603:10b6:3:6e::7) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from tlendack-t1.amd.com (165.204.77.1) by SN6PR16CA0059.namprd16.prod.outlook.com (2603:10b6:805:ca::36) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4108.25 via Frontend Transport; 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Invalidation is only required after userspace is available, so call vc_ghcb_invalidate() from sev_es_put_ghcb(). Update vc_ghcb_invalidate() to additionally clear the GHCB exit code, so that a value of 0 is always present outside VMGEXIT processing in the kernel. Fixes: 0786138c78e79 ("x86/sev-es: Add a Runtime #VC Exception Handler") Cc: stable@vger.kernel.org Signed-off-by: Tom Lendacky Reviewed-by: Joerg Roedel --- arch/x86/kernel/sev-shared.c | 1 + arch/x86/kernel/sev.c | 5 +++++ 2 files changed, 6 insertions(+) diff --git a/arch/x86/kernel/sev-shared.c b/arch/x86/kernel/sev-shared.c index 6ec8b3bfd76e..9f90f460a28c 100644 --- a/arch/x86/kernel/sev-shared.c +++ b/arch/x86/kernel/sev-shared.c @@ -63,6 +63,7 @@ static bool sev_es_negotiate_protocol(void) static __always_inline void vc_ghcb_invalidate(struct ghcb *ghcb) { + ghcb->save.sw_exit_code = 0; memset(ghcb->save.valid_bitmap, 0, sizeof(ghcb->save.valid_bitmap)); } diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c index 45e212675811..4fa111becc93 100644 --- a/arch/x86/kernel/sev.c +++ b/arch/x86/kernel/sev.c @@ -457,6 +457,11 @@ static __always_inline void sev_es_put_ghcb(struct ghcb_state *state) data->backup_ghcb_active = false; state->ghcb = NULL; } else { + /* + * Invalidate the GHCB so a VMGEXIT instruction issued + * from userspace won't appear to be valid. + */ + vc_ghcb_invalidate(ghcb); data->ghcb_active = false; } }