x86/retpoline: Fill return stack buffer on vmexit

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commit 117cc7a908 upstream.

In accordance with the Intel and AMD documentation, we need to overwrite
all entries in the RSB on exiting a guest, to prevent malicious branch
target predictions from affecting the host kernel. This is needed both
for retpoline and for IBRS.

[ak: numbers again for the RSB stuffing labels]

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: gnomes@lxorguk.ukuu.org.uk
Cc: Rik van Riel <riel@redhat.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: thomas.lendacky@amd.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Jiri Kosina <jikos@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Kees Cook <keescook@google.com>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Greg Kroah-Hartman <gregkh@linux-foundation.org>
Cc: Paul Turner <pjt@google.com>
Link: https://lkml.kernel.org/r/1515755487-8524-1-git-send-email-dwmw@amazon.co.uk
[bwh: Backported to 3.16:
 - Drop the ANNOTATE_NOSPEC_ALTERNATIVEs
 - Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

...

This commit is contained in:

David Woodhouse 2018-01-12 11:11:27 +00:00 • committed by Ben Hutchings

parent 901d43afc1

commit 20e080e275

3 changed files with 83 additions and 1 deletions

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76

arch/x86/include/asm/nospec-branch.h

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4

arch/x86/kvm/svm.c

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4

arch/x86/kvm/vmx.c

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