KVM: Handle virtualization instruction #UD faults during reboot
KVM turns off hardware virtualization extensions during reboot, in order
to disassociate the memory used by the virtualization extensions from the
processor, and in order to have the system in a consistent state.
Unfortunately virtual machines may still be running while this goes on,
and once virtualization extensions are turned off, any virtulization
instruction will #UD on execution.
Fix by adding an exception handler to virtualization instructions; if we get
an exception during reboot, we simply spin waiting for the reset to complete.
If it's a true exception, BUG() so we can have our stack trace.
Signed-off-by: Avi Kivity <avi@qumranet.com>
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index fff8e23..b80b4d1 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -30,6 +30,8 @@
#include <asm/io.h>
#include <asm/desc.h>
+#define __ex(x) __kvm_handle_fault_on_reboot(x)
+
MODULE_AUTHOR("Qumranet");
MODULE_LICENSE("GPL");
@@ -278,7 +280,7 @@
u64 gva;
} operand = { vpid, 0, gva };
- asm volatile (ASM_VMX_INVVPID
+ asm volatile (__ex(ASM_VMX_INVVPID)
/* CF==1 or ZF==1 --> rc = -1 */
"; ja 1f ; ud2 ; 1:"
: : "a"(&operand), "c"(ext) : "cc", "memory");
@@ -290,7 +292,7 @@
u64 eptp, gpa;
} operand = {eptp, gpa};
- asm volatile (ASM_VMX_INVEPT
+ asm volatile (__ex(ASM_VMX_INVEPT)
/* CF==1 or ZF==1 --> rc = -1 */
"; ja 1f ; ud2 ; 1:\n"
: : "a" (&operand), "c" (ext) : "cc", "memory");
@@ -311,7 +313,7 @@
u64 phys_addr = __pa(vmcs);
u8 error;
- asm volatile (ASM_VMX_VMCLEAR_RAX "; setna %0"
+ asm volatile (__ex(ASM_VMX_VMCLEAR_RAX) "; setna %0"
: "=g"(error) : "a"(&phys_addr), "m"(phys_addr)
: "cc", "memory");
if (error)
@@ -378,7 +380,7 @@
{
unsigned long value;
- asm volatile (ASM_VMX_VMREAD_RDX_RAX
+ asm volatile (__ex(ASM_VMX_VMREAD_RDX_RAX)
: "=a"(value) : "d"(field) : "cc");
return value;
}
@@ -413,7 +415,7 @@
{
u8 error;
- asm volatile (ASM_VMX_VMWRITE_RAX_RDX "; setna %0"
+ asm volatile (__ex(ASM_VMX_VMWRITE_RAX_RDX) "; setna %0"
: "=q"(error) : "a"(value), "d"(field) : "cc");
if (unlikely(error))
vmwrite_error(field, value);
@@ -621,7 +623,7 @@
u8 error;
per_cpu(current_vmcs, cpu) = vmx->vmcs;
- asm volatile (ASM_VMX_VMPTRLD_RAX "; setna %0"
+ asm volatile (__ex(ASM_VMX_VMPTRLD_RAX) "; setna %0"
: "=g"(error) : "a"(&phys_addr), "m"(phys_addr)
: "cc");
if (error)
@@ -1030,13 +1032,14 @@
MSR_IA32_FEATURE_CONTROL_LOCKED |
MSR_IA32_FEATURE_CONTROL_VMXON_ENABLED);
write_cr4(read_cr4() | X86_CR4_VMXE); /* FIXME: not cpu hotplug safe */
- asm volatile (ASM_VMX_VMXON_RAX : : "a"(&phys_addr), "m"(phys_addr)
+ asm volatile (ASM_VMX_VMXON_RAX
+ : : "a"(&phys_addr), "m"(phys_addr)
: "memory", "cc");
}
static void hardware_disable(void *garbage)
{
- asm volatile (ASM_VMX_VMXOFF : : : "cc");
+ asm volatile (__ex(ASM_VMX_VMXOFF) : : : "cc");
write_cr4(read_cr4() & ~X86_CR4_VMXE);
}
@@ -2834,7 +2837,7 @@
"push %%edx; push %%ebp;"
"push %%ecx \n\t"
#endif
- ASM_VMX_VMWRITE_RSP_RDX "\n\t"
+ __ex(ASM_VMX_VMWRITE_RSP_RDX) "\n\t"
/* Check if vmlaunch of vmresume is needed */
"cmpl $0, %c[launched](%0) \n\t"
/* Load guest registers. Don't clobber flags. */
@@ -2869,9 +2872,9 @@
#endif
/* Enter guest mode */
"jne .Llaunched \n\t"
- ASM_VMX_VMLAUNCH "\n\t"
+ __ex(ASM_VMX_VMLAUNCH) "\n\t"
"jmp .Lkvm_vmx_return \n\t"
- ".Llaunched: " ASM_VMX_VMRESUME "\n\t"
+ ".Llaunched: " __ex(ASM_VMX_VMRESUME) "\n\t"
".Lkvm_vmx_return: "
/* Save guest registers, load host registers, keep flags */
#ifdef CONFIG_X86_64