From: Joerg Roedel <joro@8bytes.org>
To: x86@kernel.org, Hyunwook Baek <baekhw@google.com>
Cc: Joerg Roedel <joro@8bytes.org>, Joerg Roedel <jroedel@suse.de>,
stable@vger.kernel.org, hpa@zytor.com,
Andy Lutomirski <luto@kernel.org>,
Dave Hansen <dave.hansen@linux.intel.com>,
Peter Zijlstra <peterz@infradead.org>,
Jiri Slaby <jslaby@suse.cz>,
Dan Williams <dan.j.williams@intel.com>,
Tom Lendacky <thomas.lendacky@amd.com>,
Juergen Gross <jgross@suse.com>,
Kees Cook <keescook@chromium.org>,
David Rientjes <rientjes@google.com>,
Cfir Cohen <cfir@google.com>, Erdem Aktas <erdemaktas@google.com>,
Masami Hiramatsu <mhiramat@kernel.org>,
Mike Stunes <mstunes@vmware.com>,
Sean Christopherson <seanjc@google.com>,
Martin Radev <martin.b.radev@gmail.com>,
Arvind Sankar <nivedita@alum.mit.edu>,
linux-coco@lists.linux.dev, linux-kernel@vger.kernel.org,
kvm@vger.kernel.org, virtualization@lists.linux-foundation.org
Subject: [PATCH v2 1/8] x86/sev-es: Don't return NULL from sev_es_get_ghcb()
Date: Wed, 19 May 2021 15:52:44 +0200 [thread overview]
Message-ID: <20210519135251.30093-2-joro@8bytes.org> (raw)
In-Reply-To: <20210519135251.30093-1-joro@8bytes.org>
From: Joerg Roedel <jroedel@suse.de>
The sev_es_get_ghcb() is called from several places, but only one of
them checks the return value. The reaction to returning NULL is always
the same: Calling panic() and kill the machine.
Instead of adding checks to all call-places, move the panic() into the
function itself so that it will no longer return NULL.
Fixes: 0786138c78e7 ("x86/sev-es: Add a Runtime #VC Exception Handler")
Cc: stable@vger.kernel.org # v5.10+
Signed-off-by: Joerg Roedel <jroedel@suse.de>
---
arch/x86/kernel/sev.c | 25 ++++++++++++-------------
1 file changed, 12 insertions(+), 13 deletions(-)
diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c
index 4fa111becc93..82bced88153b 100644
--- a/arch/x86/kernel/sev.c
+++ b/arch/x86/kernel/sev.c
@@ -203,8 +203,18 @@ static __always_inline struct ghcb *sev_es_get_ghcb(struct ghcb_state *state)
if (unlikely(data->ghcb_active)) {
/* GHCB is already in use - save its contents */
- if (unlikely(data->backup_ghcb_active))
- return NULL;
+ if (unlikely(data->backup_ghcb_active)) {
+ /*
+ * Backup-GHCB is also already in use. There is no way
+ * to continue here so just kill the machine. To make
+ * panic() work, mark GHCBs inactive so that messages
+ * can be printed out.
+ */
+ data->ghcb_active = false;
+ data->backup_ghcb_active = false;
+
+ panic("Unable to handle #VC exception! GHCB and Backup GHCB are already in use");
+ }
/* Mark backup_ghcb active before writing to it */
data->backup_ghcb_active = true;
@@ -1289,7 +1299,6 @@ static __always_inline bool on_vc_fallback_stack(struct pt_regs *regs)
*/
DEFINE_IDTENTRY_VC_SAFE_STACK(exc_vmm_communication)
{
- struct sev_es_runtime_data *data = this_cpu_read(runtime_data);
irqentry_state_t irq_state;
struct ghcb_state state;
struct es_em_ctxt ctxt;
@@ -1315,16 +1324,6 @@ DEFINE_IDTENTRY_VC_SAFE_STACK(exc_vmm_communication)
*/
ghcb = sev_es_get_ghcb(&state);
- if (!ghcb) {
- /*
- * Mark GHCBs inactive so that panic() is able to print the
- * message.
- */
- data->ghcb_active = false;
- data->backup_ghcb_active = false;
-
- panic("Unable to handle #VC exception! GHCB and Backup GHCB are already in use");
- }
vc_ghcb_invalidate(ghcb);
result = vc_init_em_ctxt(&ctxt, regs, error_code);
--
2.31.1
next prev parent reply other threads:[~2021-05-19 13:53 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-19 13:52 [PATCH v2 0/8] x86/sev-es: Fixes for SEV-ES Guest Support Joerg Roedel
2021-05-19 13:52 ` Joerg Roedel [this message]
2021-05-19 13:52 ` [PATCH v2 2/8] x86/sev-es: Forward page-faults which happen during emulation Joerg Roedel
2021-05-19 13:52 ` [PATCH v2 3/8] x86/sev-es: Use __put_user()/__get_user() for data accesses Joerg Roedel
2021-05-19 13:52 ` [PATCH v2 4/8] x86/sev-es: Fix error message in runtime #VC handler Joerg Roedel
2021-05-19 13:52 ` [PATCH v2 5/8] x86/sev-es: Leave NMI-mode before sending signals Joerg Roedel
2021-05-19 17:54 ` Peter Zijlstra
2021-05-19 19:13 ` Joerg Roedel
2021-05-19 19:31 ` Peter Zijlstra
2021-05-19 13:52 ` [PATCH v2 6/8] x86/insn-eval: Make 0 a valid RIP for insn_get_effective_ip() Joerg Roedel
2021-05-19 13:52 ` [PATCH v2 7/8] x86/insn: Extend error reporting from insn_fetch_from_user[_inatomic]() Joerg Roedel
2021-05-21 14:34 ` Borislav Petkov
2021-05-19 13:52 ` [PATCH v2 8/8] x86/sev-es: Propagate #GP if getting linear instruction address failed Joerg Roedel
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