linux-kernel - [PATCH 0/2] KVM: VMX: Add Force Emulation Prefix for "emulate the next instruction"

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Date:   Mon, 26 Mar 2018 19:12:13 -0700
From:   Wanpeng Li <kernellwp@...il.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Andrew Cooper <andrew.cooper3@...rix.com>
Subject: [PATCH 0/2] KVM: VMX: Add Force Emulation Prefix for "emulate the next instruction"

This patchset introduces a Force Emulation Prefix (ud2a; .ascii "kvm") 
for "emulate the next instruction", the codes will be executed by emulator 
instead of processor, for testing purposes.

A testcase here:

#include <stdio.h>
#include <string.h>
   
#define HYPERVISOR_INFO 0x40000000
   
#define CPUID(idx, eax, ebx, ecx, edx)\
    asm volatile (\
    "ud2a; .ascii \"kvm\"; 1: cpuid" \
    :"=b" (*ebx), "=a" (*eax),"=c" (*ecx), "=d" (*edx)\
        :"0"(idx) );  
   
void main()  
{  
	unsigned int eax,ebx,ecx,edx;  
	char string[13];  
   
	CPUID(HYPERVISOR_INFO, &eax, &ebx, &ecx, &edx);  
	*(unsigned int *)(string+0) = ebx;  
	*(unsigned int *)(string+4) = ecx;  
	*(unsigned int *)(string+8) = edx;  
   
	string[12] = 0;  
	if (strncmp(string, "KVMKVMKVM\0\0\0",12) == 0)
		printf("kvm guest\n");  
	else  
		printf("bare hardware\n");  
}

Cc: Paolo Bonzini <pbonzini@...hat.com>
Cc: Radim Krčmář <rkrcmar@...hat.com>
Cc: Andrew Cooper <andrew.cooper3@...rix.com>

Wanpeng Li (2):
  KVM: VMX: Introduce handle_ud()
  KVM: VMX: Add Force Emulation Prefix for "emulate the next instruction"

 arch/x86/kvm/vmx.c | 38 ++++++++++++++++++++++++++++++--------
 1 file changed, 30 insertions(+), 8 deletions(-)

-- 
2.7.4