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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>,
	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 8/8] x86/sev-es: Propagate #GP if getting linear instruction address failed
Date: Wed, 19 May 2021 15:52:51 +0200	[thread overview]
Message-ID: <20210519135251.30093-9-joro@8bytes.org> (raw)
In-Reply-To: <20210519135251.30093-1-joro@8bytes.org>

From: Joerg Roedel <jroedel@suse.de>

When an instruction is fetched from user-space, segmentation needs to
be taken into account. This means that getting the linear address of
an instruction can fail. Hardware would raise a #GP
exception in that case, but the #VC exception handler would emulate it
as a page-fault.

The insn_fetch_from_user*() functions now provide the relevant
information in case of an failure. Use that and propagate a #GP when
the linear address of an instruction to fetch could not be calculated.

Signed-off-by: Joerg Roedel <jroedel@suse.de>
---
 arch/x86/kernel/sev.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c
index 1edb6cd5e308..4736290361e4 100644
--- a/arch/x86/kernel/sev.c
+++ b/arch/x86/kernel/sev.c
@@ -261,11 +261,16 @@ static enum es_result __vc_decode_user_insn(struct es_em_ctxt *ctxt)
 	int insn_bytes = 0, res;
 
 	res = insn_fetch_from_user_inatomic(ctxt->regs, buffer, &insn_bytes);
-	if (res) {
+	if (res == -EFAULT) {
 		ctxt->fi.vector     = X86_TRAP_PF;
 		ctxt->fi.error_code = X86_PF_INSTR | X86_PF_USER;
 		ctxt->fi.cr2        = ctxt->regs->ip;
 		return ES_EXCEPTION;
+	} else if (res == -EINVAL) {
+		ctxt->fi.vector     = X86_TRAP_GP;
+		ctxt->fi.error_code = 0;
+		ctxt->fi.cr2        = 0;
+		return ES_EXCEPTION;
 	}
 
 	if (!insn_decode_from_regs(&ctxt->insn, ctxt->regs, buffer, insn_bytes))
-- 
2.31.1


      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 ` [PATCH v2 1/8] x86/sev-es: Don't return NULL from sev_es_get_ghcb() Joerg Roedel
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 ` Joerg Roedel [this message]

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