All of lore.kernel.org
 help / color / mirror / Atom feed
From: Tom Lendacky <thomas.lendacky@amd.com>
To: x86@kernel.org, linux-kernel@vger.kernel.org
Cc: Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Andy Lutomirski <luto@kernel.org>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Dave Young <dyoung@redhat.com>,
	Brijesh Singh <brijesh.singh@amd.com>,
	<kexec@lists.infradead.org>
Subject: [PATCH v1 1/2] x86/mm, kexec: Fix memory corruption with SME on successive kexecs
Date: Wed, 26 Jul 2017 13:04:33 -0500	[thread overview]
Message-ID: <28648b23b9957506069e20bd985e3d7e8af94780.1501092102.git.thomas.lendacky@amd.com> (raw)
In-Reply-To: <cover.1501092102.git.thomas.lendacky@amd.com>

After issuing successive kexecs it was found that the SHA hash failed
verification when booting the kexec'd kernel.  When SME is enabled, the
change from using pages that were marked encrypted to now being marked as
not encrypted (through new identify mapped page tables) results in memory
corruption if there are any cache entries for the previously encrypted
pages. This is because separate cache entries can exist for the same
physical location but tagged both with and without the encryption bit.

To prevent this, issue a wbinvd before copying the pages from the source
location to the destination location to clear any possible cache entry
conflicts.

Cc: <kexec@lists.infradead.org>
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
---
 arch/x86/kernel/relocate_kernel_64.S | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/arch/x86/kernel/relocate_kernel_64.S b/arch/x86/kernel/relocate_kernel_64.S
index 98111b3..c11d8bc 100644
--- a/arch/x86/kernel/relocate_kernel_64.S
+++ b/arch/x86/kernel/relocate_kernel_64.S
@@ -132,6 +132,13 @@ identity_mapped:
 	/* Flush the TLB (needed?) */
 	movq	%r9, %cr3
 
+	/*
+	 * If SME is/was active, there could be old encrypted cache line
+	 * entries that will conflict with the now unencrypted memory
+	 * used by kexec. Flush the caches before copying the kernel.
+	 */
+	wbinvd
+
 	movq	%rcx, %r11
 	call	swap_pages
 
-- 
1.9.1

WARNING: multiple messages have this Message-ID (diff)
From: Tom Lendacky <thomas.lendacky@amd.com>
To: x86@kernel.org, linux-kernel@vger.kernel.org
Cc: Brijesh Singh <brijesh.singh@amd.com>,
	kexec@lists.infradead.org, Ingo Molnar <mingo@redhat.com>,
	Borislav Petkov <bp@alien8.de>, Andy Lutomirski <luto@kernel.org>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Dave Young <dyoung@redhat.com>
Subject: [PATCH v1 1/2] x86/mm, kexec: Fix memory corruption with SME on successive kexecs
Date: Wed, 26 Jul 2017 13:04:33 -0500	[thread overview]
Message-ID: <28648b23b9957506069e20bd985e3d7e8af94780.1501092102.git.thomas.lendacky@amd.com> (raw)
In-Reply-To: <cover.1501092102.git.thomas.lendacky@amd.com>

After issuing successive kexecs it was found that the SHA hash failed
verification when booting the kexec'd kernel.  When SME is enabled, the
change from using pages that were marked encrypted to now being marked as
not encrypted (through new identify mapped page tables) results in memory
corruption if there are any cache entries for the previously encrypted
pages. This is because separate cache entries can exist for the same
physical location but tagged both with and without the encryption bit.

To prevent this, issue a wbinvd before copying the pages from the source
location to the destination location to clear any possible cache entry
conflicts.

Cc: <kexec@lists.infradead.org>
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
---
 arch/x86/kernel/relocate_kernel_64.S | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/arch/x86/kernel/relocate_kernel_64.S b/arch/x86/kernel/relocate_kernel_64.S
index 98111b3..c11d8bc 100644
--- a/arch/x86/kernel/relocate_kernel_64.S
+++ b/arch/x86/kernel/relocate_kernel_64.S
@@ -132,6 +132,13 @@ identity_mapped:
 	/* Flush the TLB (needed?) */
 	movq	%r9, %cr3
 
+	/*
+	 * If SME is/was active, there could be old encrypted cache line
+	 * entries that will conflict with the now unencrypted memory
+	 * used by kexec. Flush the caches before copying the kernel.
+	 */
+	wbinvd
+
 	movq	%rcx, %r11
 	call	swap_pages
 
-- 
1.9.1


_______________________________________________
kexec mailing list
kexec@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/kexec

  reply	other threads:[~2017-07-26 18:05 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-07-26 18:04 [PATCH v1 0/2] x86: Secure Memory Encryption (SME) fixes 2017-07-26 Tom Lendacky
2017-07-26 18:04 ` Tom Lendacky
2017-07-26 18:04 ` Tom Lendacky [this message]
2017-07-26 18:04   ` [PATCH v1 1/2] x86/mm, kexec: Fix memory corruption with SME on successive kexecs Tom Lendacky
2017-07-27  7:17   ` Ingo Molnar
2017-07-27  7:17     ` Ingo Molnar
2017-07-27 14:15     ` Tom Lendacky
2017-07-27 14:15       ` Tom Lendacky
2017-07-27 17:34       ` Linus Torvalds
2017-07-27 17:34         ` Linus Torvalds
2017-07-27 18:47         ` Tom Lendacky
2017-07-27 18:47           ` Tom Lendacky
2017-07-26 18:04 ` [PATCH v1 2/2] acpi, x86: Remove encryption mask from ACPI page protection type Tom Lendacky
2017-07-27  7:39   ` Ingo Molnar
2017-07-27 14:53     ` Tom Lendacky
2017-07-27 14:41   ` Borislav Petkov
2017-07-27 14:57     ` Tom Lendacky
2017-07-28  6:28       ` Ingo Molnar

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=28648b23b9957506069e20bd985e3d7e8af94780.1501092102.git.thomas.lendacky@amd.com \
    --to=thomas.lendacky@amd.com \
    --cc=bp@alien8.de \
    --cc=brijesh.singh@amd.com \
    --cc=dyoung@redhat.com \
    --cc=hpa@zytor.com \
    --cc=kexec@lists.infradead.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=luto@kernel.org \
    --cc=mingo@redhat.com \
    --cc=tglx@linutronix.de \
    --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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.