Commit 35a78319 authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
Browse files

KVM: SVM: Use asm goto to handle unexpected #UD on SVM instructions 



Add svm_asm*() macros, a la the existing vmx_asm*() macros, to handle
faults on SVM instructions instead of using the generic __ex(), a.k.a.
__kvm_handle_fault_on_reboot().  Using asm goto generates slightly
better code as it eliminates the in-line JMP+CALL sequences that are
needed by __kvm_handle_fault_on_reboot() to avoid triggering BUG()
from fixup (which generates bad stack traces).

Using SVM specific macros also drops the last user of __ex() and the
the last asm linkage to kvm_spurious_fault(), and adds a helper for
VMSAVE, which may gain an addition call site in the future (as part
of optimizing the SVM context switching).

Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
Message-Id: <20201231002702.22237077-8-seanjc@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 6a289139

arch/x86/kvm/svm/sev.c

+2 −1
Original line number Diff line number Diff line
@@ -22,6 +22,7 @@ 


#include "x86.h"

#include "svm.h"

#include "svm_ops.h"

#include "cpuid.h"

#include "trace.h"
@@ -2076,7 +2077,7 @@ void sev_es_vcpu_load(struct vcpu_svm *svm, int cpu) 
	 * of which one step is to perform a VMLOAD. Since hardware does not

	 * perform a VMSAVE on VMRUN, the host savearea must be updated.

	 */

	asm volatile(__ex("vmsave %0") : : "a" (__sme_page_pa(sd->save_area)) : "memory");

	vmsave(__sme_page_pa(sd->save_area));



	/*

	 * Certain MSRs are restored on VMEXIT, only save ones that aren't

arch/x86/kvm/svm/svm.c

+1 −15
Original line number Diff line number Diff line
@@ -41,6 +41,7 @@ 
#include "trace.h"



#include "svm.h"

#include "svm_ops.h"



#define __ex(x) __kvm_handle_fault_on_reboot(x)
@@ -248,21 +249,6 @@ u32 svm_msrpm_offset(u32 msr) 


#define MAX_INST_SIZE 15



static inline void clgi(void)

{

	asm volatile (__ex("clgi"));

}



static inline void stgi(void)

{

	asm volatile (__ex("stgi"));

}



static inline void invlpga(unsigned long addr, u32 asid)

{

	asm volatile (__ex("invlpga %1, %0") : : "c"(asid), "a"(addr));

}



static int get_max_npt_level(void)

{

#ifdef CONFIG_X86_64

arch/x86/kvm/svm/svm_ops.h

0 → 100644
+64 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0 */

#ifndef __KVM_X86_SVM_OPS_H

#define __KVM_X86_SVM_OPS_H



#include <linux/compiler_types.h>



#include <asm/kvm_host.h>



#define svm_asm(insn, clobber...)				\

do {								\

	asm_volatile_goto("1: " __stringify(insn) "\n\t"	\

			  _ASM_EXTABLE(1b, %l[fault])		\

			  ::: clobber : fault);			\

	return;							\

fault:								\

	kvm_spurious_fault();					\

} while (0)



#define svm_asm1(insn, op1, clobber...)				\

do {								\

	asm_volatile_goto("1: "  __stringify(insn) " %0\n\t"	\

			  _ASM_EXTABLE(1b, %l[fault])		\

			  :: op1 : clobber : fault);		\

	return;							\

fault:								\

	kvm_spurious_fault();					\

} while (0)



#define svm_asm2(insn, op1, op2, clobber...)				\

do {									\

	asm_volatile_goto("1: "  __stringify(insn) " %1, %0\n\t"	\

			  _ASM_EXTABLE(1b, %l[fault])			\

			  :: op1, op2 : clobber : fault);		\

	return;								\

fault:									\

	kvm_spurious_fault();						\

} while (0)



static inline void clgi(void)

{

	svm_asm(clgi);

}



static inline void stgi(void)

{

	svm_asm(stgi);

}



static inline void invlpga(unsigned long addr, u32 asid)

{

	svm_asm2(invlpga, "c"(asid), "a"(addr));

}



/*

 * Despite being a physical address, the portion of rAX that is consumed by

 * VMSAVE, VMLOAD, etc... is still controlled by the effective address size,

 * hence 'unsigned long' instead of 'hpa_t'.

 */

static inline void vmsave(unsigned long pa)

{

	svm_asm1(vmsave, "a" (pa), "memory");

}



#endif /* __KVM_X86_SVM_OPS_H */