Commit b3dc0695 authored by Masami Hiramatsu's avatar Masami Hiramatsu Committed by Peter Zijlstra
Browse files

x86: xen: kvm: Gather the definition of emulate prefixes 



Gather the emulate prefixes, which forcibly make the following
instruction emulated on virtualization, in one place.

Suggested-by: default avatarPeter Zijlstra <peterz@infradead.org>
Signed-off-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Juergen Gross <jgross@suse.com>
Cc: x86@kernel.org
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Stefano Stabellini <sstabellini@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: xen-devel@lists.xenproject.org
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/156777563917.25081.7286628561790289995.stgit@devnote2
parent f7919fd9

arch/x86/include/asm/emulate_prefix.h

0 → 100644
+14 −0
Original line number Diff line number Diff line 
/* 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

arch/x86/include/asm/xen/interface.h

+4 −7
Original line number Diff line number Diff line
@@ -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 */

arch/x86/kvm/x86.c

+3 −1
Original line number Diff line number Diff line
@@ -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
@@ -5446,6 +5447,7 @@ EXPORT_SYMBOL_GPL(kvm_write_guest_virt_system); 


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;
@@ -5453,7 +5455,7 @@ 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;

	}

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