This is a note to let you know that I've just added the patch titled
x86: xen: kvm: Gather the definition of emulate prefixes
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
x86-xen-kvm-gather-the-definition-of-emulate-prefixes.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <sta...@vger.kernel.org> know about it.
>From b3dc0695fa40c3b280230fb6fb7fb7a94ce28bf4 Mon Sep 17 00:00:00 2001
From: Masami Hiramatsu <mhira...@kernel.org>
Date: Fri, 6 Sep 2019 22:13:59 +0900
Subject: x86: xen: kvm: Gather the definition of emulate prefixes
From: Masami Hiramatsu <mhira...@kernel.org>
commit b3dc0695fa40c3b280230fb6fb7fb7a94ce28bf4 upstream.
Gather the emulate prefixes, which forcibly make the following
instruction emulated on virtualization, in one place.
Suggested-by: Peter Zijlstra <pet...@infradead.org>
Signed-off-by: Masami Hiramatsu <mhira...@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org>
Cc: Juergen Gross <jgr...@suse.com>
Cc: x...@kernel.org
Cc: Ingo Molnar <mi...@kernel.org>
Cc: Boris Ostrovsky <boris.ostrov...@oracle.com>
Cc: Andrew Cooper <andrew.coop...@citrix.com>
Cc: Stefano Stabellini <sstabell...@kernel.org>
Cc: Borislav Petkov <b...@alien8.de>
Cc: xen-devel@lists.xenproject.org
Cc: Randy Dunlap <rdun...@infradead.org>
Cc: Josh Poimboeuf <jpoim...@redhat.com>
Link:
https://lkml.kernel.org/r/156777563917.25081.7286628561790289995.stgit@devnote2
Signed-off-by: Maximilian Heyne <mhe...@amazon.de>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
arch/x86/include/asm/emulate_prefix.h | 14 ++++++++++++++
arch/x86/include/asm/xen/interface.h | 11 ++++-------
arch/x86/kvm/x86.c | 4 +++-
3 files changed, 21 insertions(+), 8 deletions(-)
create mode 100644 arch/x86/include/asm/emulate_prefix.h
--- /dev/null
+++ b/arch/x86/include/asm/emulate_prefix.h
@@ -0,0 +1,14 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_X86_EMULATE_PREFIX_H
+#define _ASM_X86_EMULATE_PREFIX_H
+
+/*
+ * Virt escape sequences to trigger instruction emulation;
+ * ideally these would decode to 'whole' instruction and not destroy
+ * the instruction stream; sadly this is not true for the 'kvm' one :/
+ */
+
+#define __XEN_EMULATE_PREFIX 0x0f,0x0b,0x78,0x65,0x6e /* ud2 ; .ascii "xen"
*/
+#define __KVM_EMULATE_PREFIX 0x0f,0x0b,0x6b,0x76,0x6d /* ud2 ; .ascii "kvm" */
+
+#endif
--- a/arch/x86/include/asm/xen/interface.h
+++ b/arch/x86/include/asm/xen/interface.h
@@ -379,12 +379,9 @@ struct xen_pmu_arch {
* Prefix forces emulation of some non-trapping instructions.
* Currently only CPUID.
*/
-#ifdef __ASSEMBLY__
-#define XEN_EMULATE_PREFIX .byte 0x0f,0x0b,0x78,0x65,0x6e ;
-#define XEN_CPUID XEN_EMULATE_PREFIX cpuid
-#else
-#define XEN_EMULATE_PREFIX ".byte 0x0f,0x0b,0x78,0x65,0x6e ; "
-#define XEN_CPUID XEN_EMULATE_PREFIX "cpuid"
-#endif
+#include <asm/emulate_prefix.h>
+
+#define XEN_EMULATE_PREFIX __ASM_FORM(.byte __XEN_EMULATE_PREFIX ;)
+#define XEN_CPUID XEN_EMULATE_PREFIX __ASM_FORM(cpuid)
#endif /* _ASM_X86_XEN_INTERFACE_H */
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -68,6 +68,7 @@
#include <asm/mshyperv.h>
#include <asm/hypervisor.h>
#include <asm/intel_pt.h>
+#include <asm/emulate_prefix.h>
#include <clocksource/hyperv_timer.h>
#define CREATE_TRACE_POINTS
@@ -5583,6 +5584,7 @@ EXPORT_SYMBOL_GPL(kvm_write_guest_virt_s
int handle_ud(struct kvm_vcpu *vcpu)
{
+ static const char kvm_emulate_prefix[] = { __KVM_EMULATE_PREFIX };
int emul_type = EMULTYPE_TRAP_UD;
char sig[5]; /* ud2; .ascii "kvm" */
struct x86_exception e;
@@ -5590,7 +5592,7 @@ int handle_ud(struct kvm_vcpu *vcpu)
if (force_emulation_prefix &&
kvm_read_guest_virt(vcpu, kvm_get_linear_rip(vcpu),
sig, sizeof(sig), &e) == 0 &&
- memcmp(sig, "\xf\xbkvm", sizeof(sig)) == 0) {
+ memcmp(sig, kvm_emulate_prefix, sizeof(sig)) == 0) {
kvm_rip_write(vcpu, kvm_rip_read(vcpu) + sizeof(sig));
emul_type = EMULTYPE_TRAP_UD_FORCED;
}
Patches currently in stable-queue which might be from mhira...@kernel.org are
queue-5.4/x86-xen-kvm-gather-the-definition-of-emulate-prefixes.patch
queue-5.4/x86-xen-insn-decode-xen-and-kvm-emulate-prefix-signature.patch
queue-5.4/x86-asm-allow-to-pass-macros-to-__asm_form.patch
queue-5.4/x86-kprobes-prohibit-probing-on-instruction-which-has-emulate-prefix.patch
