Commit 6e202097 authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
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KVM: VMX: Add error handling to VMREAD helper 



Now that VMREAD flows require a taken branch, courtesy of commit

  3901336e ("x86/kvm: Don't call kvm_spurious_fault() from .fixup")

bite the bullet and add full error handling to VMREAD, i.e. replace the
JMP added by __ex()/____kvm_handle_fault_on_reboot() with a hinted Jcc.

To minimize the code footprint, add a helper function, vmread_error(),
to handle both faults and failures so that the inline flow has a single
CALL.

Acked-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: default avatarSean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 52a9fcbc

arch/x86/kvm/vmx/ops.h

+17 −4
Original line number Diff line number Diff line
@@ -11,9 +11,8 @@ 
#include "vmcs.h"



#define __ex(x) __kvm_handle_fault_on_reboot(x)

#define __ex_clear(x, reg) \

	____kvm_handle_fault_on_reboot(x, "xor " reg ", " reg)



asmlinkage void vmread_error(unsigned long field, bool fault);

void vmwrite_error(unsigned long field, unsigned long value);

void vmclear_error(struct vmcs *vmcs, u64 phys_addr);

void vmptrld_error(struct vmcs *vmcs, u64 phys_addr);
@@ -68,8 +67,22 @@ static __always_inline unsigned long __vmcs_readl(unsigned long field) 
{

	unsigned long value;



	asm volatile (__ex_clear("vmread %1, %0", "%k0")

		      : "=r"(value) : "r"(field));

	asm volatile("1: vmread %2, %1\n\t"

		     ".byte 0x3e\n\t" /* branch taken hint */

		     "ja 3f\n\t"

		     "mov %2, %%" _ASM_ARG1 "\n\t"

		     "xor %%" _ASM_ARG2 ", %%" _ASM_ARG2 "\n\t"

		     "2: call vmread_error\n\t"

		     "xor %k1, %k1\n\t"

		     "3:\n\t"



		     ".pushsection .fixup, \"ax\"\n\t"

		     "4: mov %2, %%" _ASM_ARG1 "\n\t"

		     "mov $1, %%" _ASM_ARG2 "\n\t"

		     "jmp 2b\n\t"

		     ".popsection\n\t"

		     _ASM_EXTABLE(1b, 4b)

		     : ASM_CALL_CONSTRAINT, "=r"(value) : "r"(field) : "cc");

	return value;

}

arch/x86/kvm/vmx/vmx.c

+8 −0
Original line number Diff line number Diff line
@@ -349,6 +349,14 @@ do { \ 
	pr_warn_ratelimited(fmt);	\

} while (0)



asmlinkage void vmread_error(unsigned long field, bool fault)

{

	if (fault)

		kvm_spurious_fault();

	else

		vmx_insn_failed("kvm: vmread failed: field=%lx\n", field);

}



noinline void vmwrite_error(unsigned long field, unsigned long value)

{

	vmx_insn_failed("kvm: vmwrite failed: field=%lx val=%lx err=%d\n",

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