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 4/6] Revert "x86/sev-es: Handle string port IO to kernel memory properly"
Date: Wed, 12 May 2021 09:54:43 +0200 [thread overview]
Message-ID: <20210512075445.18935-5-joro@8bytes.org> (raw)
In-Reply-To: <20210512075445.18935-1-joro@8bytes.org>
From: Joerg Roedel <jroedel@suse.de>
This reverts commit 7024f60d655272bd2ca1d3a4c9e0a63319b1eea1.
The commit reverted here introduces a short-cut into the #VC handlers
memory access code which only works reliably in task context. But the
kernels #VC handler can be invoked from any context, making the
access_ok() call trigger a warning with CONFIG_DEBUG_ATOMIC_SLEEP
enabled.
Also the memcpy() used in the reverted patch is wrong, as it has no
page-fault handling. Access to kernel memory can also fault due to
kernel bugs, and those should not be reported as faults from the #VC
handler but as bugs of their real call-site, which is correctly later
done from vc_forward_exception().
Fixes: 7024f60d6552 ("x86/sev-es: Handle string port IO to kernel memory properly")
Cc: stable@vger.kernel.org # v5.11
Signed-off-by: Joerg Roedel <jroedel@suse.de>
---
arch/x86/kernel/sev.c | 12 ------------
1 file changed, 12 deletions(-)
diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c
index 110b39345b40..f4f319004713 100644
--- a/arch/x86/kernel/sev.c
+++ b/arch/x86/kernel/sev.c
@@ -333,12 +333,6 @@ static enum es_result vc_write_mem(struct es_em_ctxt *ctxt,
u16 d2;
u8 d1;
- /* If instruction ran in kernel mode and the I/O buffer is in kernel space */
- if (!user_mode(ctxt->regs) && !access_ok(target, size)) {
- memcpy(dst, buf, size);
- return ES_OK;
- }
-
switch (size) {
case 1:
memcpy(&d1, buf, 1);
@@ -388,12 +382,6 @@ static enum es_result vc_read_mem(struct es_em_ctxt *ctxt,
u16 d2;
u8 d1;
- /* If instruction ran in kernel mode and the I/O buffer is in kernel space */
- if (!user_mode(ctxt->regs) && !access_ok(s, size)) {
- memcpy(buf, src, size);
- return ES_OK;
- }
-
switch (size) {
case 1:
if (__get_user(d1, s))
--
2.31.1
next prev parent reply other threads:[~2021-05-12 7:55 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-12 7:54 [PATCH 0/6] x86/sev-es: Fixes for SEV-ES guest support Joerg Roedel
2021-05-12 7:54 ` [PATCH 1/6] x86/sev-es: Don't return NULL from sev_es_get_ghcb() Joerg Roedel
2021-05-12 7:54 ` [PATCH 2/6] x86/sev-es: Forward page-faults which happen during emulation Joerg Roedel
2021-05-12 17:31 ` Sean Christopherson
2021-05-19 13:16 ` Joerg Roedel
2021-05-12 7:54 ` [PATCH 3/6] x86/sev-es: Use __put_user()/__get_user Joerg Roedel
2021-05-12 8:04 ` David Laight
2021-05-12 8:16 ` Juergen Gross
2021-05-12 8:50 ` 'Joerg Roedel'
2021-05-12 8:58 ` Juergen Gross
2021-05-12 9:31 ` David Laight
2021-05-12 9:32 ` Joerg Roedel
2021-05-19 11:33 ` 'Joerg Roedel'
2021-05-12 8:37 ` 'Joerg Roedel'
2021-05-12 15:59 ` Dave Hansen
2021-05-12 15:57 ` Dave Hansen
2021-05-12 16:00 ` Joerg Roedel
2021-05-12 7:54 ` Joerg Roedel [this message]
2021-05-12 17:38 ` [PATCH 4/6] Revert "x86/sev-es: Handle string port IO to kernel memory properly" Sean Christopherson
2021-05-19 12:22 ` Joerg Roedel
2021-05-12 7:54 ` [PATCH 5/6] x86/sev-es: Fix error message in runtime #VC handler Joerg Roedel
2021-05-12 7:54 ` [PATCH 6/6] x86/sev-es: Leave NMI-mode before sending signals Joerg Roedel
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20210512075445.18935-5-joro@8bytes.org \
--to=joro@8bytes.org \
--cc=baekhw@google.com \
--cc=cfir@google.com \
--cc=dan.j.williams@intel.com \
--cc=dave.hansen@linux.intel.com \
--cc=erdemaktas@google.com \
--cc=hpa@zytor.com \
--cc=jgross@suse.com \
--cc=jroedel@suse.de \
--cc=jslaby@suse.cz \
--cc=keescook@chromium.org \
--cc=kvm@vger.kernel.org \
--cc=linux-coco@lists.linux.dev \
--cc=linux-kernel@vger.kernel.org \
--cc=luto@kernel.org \
--cc=martin.b.radev@gmail.com \
--cc=mhiramat@kernel.org \
--cc=mstunes@vmware.com \
--cc=nivedita@alum.mit.edu \
--cc=peterz@infradead.org \
--cc=rientjes@google.com \
--cc=seanjc@google.com \
--cc=stable@vger.kernel.org \
--cc=thomas.lendacky@amd.com \
--cc=virtualization@lists.linux-foundation.org \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).