From: Avi Kivity 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 Signed-off-by: Andrew Morton --- drivers/kvm/kvm_main.c | 9 ++++++--- 1 files changed, 6 insertions(+), 3 deletions(-) diff -puN drivers/kvm/kvm_main.c~kvm-avoid-using-vmx-instruction-directly-fix-asm-constraints drivers/kvm/kvm_main.c --- a/drivers/kvm/kvm_main.c~kvm-avoid-using-vmx-instruction-directly-fix-asm-constraints +++ a/drivers/kvm/kvm_main.c @@ -403,7 +403,8 @@ 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); @@ -446,7 +447,8 @@ 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); @@ -569,7 +571,8 @@ 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) _