[PATCH] KVM: Avoid using vmx instruction directly

Avi Kivity
2006-11-09T11:08:52Z

Some users have an older assembler installed which doesn't grok the
vmx instructions.

Fix by encoding the instruction opcodes directly.

Signed-off-by: Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org>

Index: linux-2.6/drivers/kvm/kvm.h
===================================================================
--- linux-2.6.orig/drivers/kvm/kvm.h
+++ linux-2.6/drivers/kvm/kvm.h
@@ -377,6 +377,16 @@ static inline struct kvm_mmu_page *page_
return (struct kvm_mmu_page *)page->private;
}

+#define ASM_VMX_VMCLEAR_RAX ".byte 0x66, 0x0f, 0xc7, 0x30"
+#define ASM_VMX_VMLAUNCH ".byte 0x0f, 0x01, 0xc2"
+#define ASM_VMX_VMRESUME ".byte 0x0f, 0x01, 0xc3"
+#define ASM_VMX_VMPTRLD_RAX ".byte 0x0f, 0xc7, 0x30"
+#define ASM_VMX_VMREAD_RDX_RAX ".byte 0x0f, 0x78, 0xd0"
+#define ASM_VMX_VMWRITE_RAX_RDX ".byte 0x0f, 0x79, 0xd0"
+#define ASM_VMX_VMWRITE_RSP_RDX ".byte 0x0f, 0x79, 0xd4"
+#define ASM_VMX_VMXOFF ".byte 0x0f, 0x01, 0xc4"
+#define ASM_VMX_VMXON_RAX ".byte 0xf3, 0x0f, 0xc7, 0x30"
+
#ifdef __x86_64__

/*
Index: linux-2.6/drivers/kvm/kvm_main.c
===================================================================
--- linux-2.6.orig/drivers/kvm/kvm_main.c
+++ linux-2.6/drivers/kvm/kvm_main.c
@@ -369,8 +369,8 @@ static void vmcs_clear(struct vmcs *vmcs
u64 phys_addr = __pa(vmcs);
u8 error;

- asm volatile ("vmclear %1; setna %0"
- : "=m"(error) : "m"(phys_addr) : "cc", "memory" );
+ asm volatile (ASM_VMX_VMCLEAR_RAX "; setna %0"
+ : "=g"(error) : "a"(&phys_addr) : "cc", "memory" );
if (error)
printk(KERN_ERR "kvm: vmclear fail: %p/%llx\n",
vmcs, phys_addr);
@@ -412,8 +412,8 @@ static struct kvm_vcpu *__vcpu_load(stru
u8 error;

per_cpu(current_vmcs, cpu) = vcpu->vmcs;
- asm volatile ("vmptrld %1; setna %0"
- : "=m"(error) : "m"(phys_addr) : "cc" );
+ asm volatile (ASM_VMX_VMPTRLD_RAX "; setna %0"
+ : "=g"(error) : "a"(&phys_addr) : "cc" );
if (error)
printk(KERN_ERR "kvm: vmptrld %p/%llx fail\n",
vcpu->vmcs, phys_addr);
@@ -536,12 +536,12 @@ static __init void kvm_enable(void *garb
/* enable and lock */
wrmsrl(MSR_IA32_FEATURE_CONTROL, old | 5);
write_cr4(read_cr4() | CR4_VMXE); /* FIXME: not cpu hotplug safe */
- asm volatile ("vmxon %0" : : "m"(phys_addr) : "memory", "cc");
+ asm volatile (ASM_VMX_VMXON_RAX : : "a"(&phys_addr) : "memory", "cc");
}

static void kvm_disable(void *garbage)
{
- asm volatile ("vmxoff" : : : "cc");
+ asm volatile (ASM_VMX_VMXOFF : : : "cc");
}

static int kvm_dev_open(struct inode *inode, struct file *filp)
@@ -633,7 +633,8 @@ unsigned long vmcs_readl(unsigned long f
{
unsigned long value;

- asm volatile ("vmread %1, %0" : "=g"(value) : "r"(field) : "cc");
+ asm volatile (ASM_VMX_VMREAD_RDX_RAX
+ : "=a"(value) : "d"(field) : "cc");
return value;
}

@@ -641,8 +642,8 @@ void vmcs_writel(unsigned long field, un
{
u8 error;

- asm volatile ("vmwrite %1, %2; setna %0"
- : "=g"(error) : "r"(value), "r"(field) : "cc" );
+ asm volatile (ASM_VMX_VMWRITE_RAX_RDX "; setna %0"
+ : "=q"(error) : "a"(value), "d"(field) : "cc" );
if (error)
printk(KERN_ERR "vmwrite error: reg %lx value %lx (err %d)\n",
field, value, vmcs_read32(VM_INSTRUCTION_ERROR));
@@ -2634,10 +2635,10 @@ again:
"push %%r8; push %%r9; push %%r10; push %%r11;"
"push %%r12; push %%r13; push %%r14; push %%r15;"
"push %%rcx \n\t"
- "vmwrite %%rsp, %2 \n\t"
+ ASM_VMX_VMWRITE_RSP_RDX "\n\t"
#else
"pusha; push %%ecx \n\t"
- "vmwrite %%esp, %2 \n\t"
+ ASM_VMX_VMWRITE_RSP_RDX "\n\t"
#endif
/* Check if vmlaunch of vmresume is needed */
"cmp $0, %1 \n\t"
@@ -2673,9 +2674,9 @@ again:
#endif
/* Enter guest mode */
"jne launched \n\t"
- "vmlaunch \n\t"
+ ASM_VMX_VMLAUNCH "\n\t"
"jmp kvm_vmx_return \n\t"
- "launched: vmresume \n\t"
+ "launched: " ASM_VMX_VMRESUME "\n\t"
".globl kvm_vmx_return \n\t"
"kvm_vmx_return: "
/* Save guest registers, load host registers, keep flags */
@@ -2722,7 +2723,7 @@ again:
"setbe %0 \n\t"
"popf \n\t"
: "=g" (fail)
- : "r"(vcpu->launched), "r"((unsigned long)HOST_RSP),
+ : "r"(vcpu->launched), "d"((unsigned long)HOST_RSP),
"c"(vcpu),
[rax]"i"(offsetof(struct kvm_vcpu, regs[VCPU_REGS_RAX])),
[rbx]"i"(offsetof(struct kvm_vcpu, regs[VCPU_REGS_RBX])),

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