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Commit 32b35627 authored by Avi Kivity's avatar Avi Kivity Committed by Linus Torvalds
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[PATCH] KVM: MMU: Fix cmpxchg8b emulation 



cmpxchg8b uses edx:eax as the compare operand, not edi:eax.

cmpxchg8b is used by 32-bit pae guests to set page table entries atomically,
and this is emulated touching shadowed guest page tables.

Also, implement it for 32-bit hosts.

Signed-off-by: default avatarAvi Kivity <avi@qumranet.com>
Acked-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 3bb65a22

drivers/kvm/kvm_main.c

+27 −0
Original line number Diff line number Diff line
@@ -936,6 +936,30 @@ static int emulator_cmpxchg_emulated(unsigned long addr, 
	return emulator_write_emulated(addr, new, bytes, ctxt);

}



#ifdef CONFIG_X86_32



static int emulator_cmpxchg8b_emulated(unsigned long addr,

				       unsigned long old_lo,

				       unsigned long old_hi,

				       unsigned long new_lo,

				       unsigned long new_hi,

				       struct x86_emulate_ctxt *ctxt)

{

	static int reported;

	int r;



	if (!reported) {

		reported = 1;

		printk(KERN_WARNING "kvm: emulating exchange8b as write\n");

	}

	r = emulator_write_emulated(addr, new_lo, 4, ctxt);

	if (r != X86EMUL_CONTINUE)

		return r;

	return emulator_write_emulated(addr+4, new_hi, 4, ctxt);

}



#endif



static unsigned long get_segment_base(struct kvm_vcpu *vcpu, int seg)

{

	return kvm_arch_ops->get_segment_base(vcpu, seg);
@@ -1010,6 +1034,9 @@ struct x86_emulate_ops emulate_ops = { 
	.read_emulated       = emulator_read_emulated,

	.write_emulated      = emulator_write_emulated,

	.cmpxchg_emulated    = emulator_cmpxchg_emulated,

#ifdef CONFIG_X86_32

	.cmpxchg8b_emulated  = emulator_cmpxchg8b_emulated,

#endif

};



int emulate_instruction(struct kvm_vcpu *vcpu,

drivers/kvm/x86_emulate.c

+1 −1
Original line number Diff line number Diff line
@@ -1323,7 +1323,7 @@ twobyte_special_insn: 
							 ctxt)) != 0))

				goto done;

			if ((old_lo != _regs[VCPU_REGS_RAX])

			    || (old_hi != _regs[VCPU_REGS_RDI])) {

			    || (old_hi != _regs[VCPU_REGS_RDX])) {

				_regs[VCPU_REGS_RAX] = old_lo;

				_regs[VCPU_REGS_RDX] = old_hi;

				_eflags &= ~EFLG_ZF;