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Subject[PATCH] KVM: Fix asm constraints
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The change to directly encoded vmx opcodes (rather than asm instructions)
forced us to pass the address of phys_addr as an operand, rather than its
contents. However, nothing forces gcc to commit the contents of the
variable to memory, so add an explicit "m" constraint.

Signed-off-by: Avi Kivity <avi@qumranet.com>

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
@@ -371,7 +371,8 @@ static void vmcs_clear(struct vmcs *vmcs
u8 error;

asm volatile (ASM_VMX_VMCLEAR_RAX "; setna %0"
- : "=g"(error) : "a"(&phys_addr) : "cc", "memory" );
+ : "=g"(error) : "a"(&phys_addr), "m"(phys_addr)
+ : "cc", "memory");
if (error)
printk(KERN_ERR "kvm: vmclear fail: %p/%llx\n",
vmcs, phys_addr);
@@ -414,7 +415,8 @@ static struct kvm_vcpu *__vcpu_load(stru

per_cpu(current_vmcs, cpu) = vcpu->vmcs;
asm volatile (ASM_VMX_VMPTRLD_RAX "; setna %0"
- : "=g"(error) : "a"(&phys_addr) : "cc" );
+ : "=g"(error) : "a"(&phys_addr), "m"(phys_addr)
+ : "cc");
if (error)
printk(KERN_ERR "kvm: vmptrld %p/%llx fail\n",
vcpu->vmcs, phys_addr);
@@ -537,7 +539,8 @@ 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 (ASM_VMX_VMXON_RAX : : "a"(&phys_addr) : "memory", "cc");
+ asm volatile (ASM_VMX_VMXON_RAX : : "a"(&phys_addr), "m"(phys_addr)
+ : "memory", "cc");
}

static void kvm_disable(void *garbage)
-
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