Commit 0cb5762e authored by Andre Przywara's avatar Andre Przywara Committed by Avi Kivity
Browse files

KVM: Allow emulation of syscalls instructions on #UD 



Add the opcodes for syscall, sysenter and sysexit to the list of instructions
handled by the undefined opcode handler.

Signed-off-by: default avatarChristoph Egger <christoph.egger@amd.com>
Signed-off-by: default avatarAmit Shah <amit.shah@redhat.com>
Signed-off-by: default avatarAndre Przywara <andre.przywara@amd.com>
Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
parent 229456fc

arch/x86/kvm/x86.c

+26 −7
Original line number Diff line number Diff line
@@ -2667,14 +2667,33 @@ int emulate_instruction(struct kvm_vcpu *vcpu, 


		r = x86_decode_insn(&vcpu->arch.emulate_ctxt, &emulate_ops);



		/* Reject the instructions other than VMCALL/VMMCALL when

		 * try to emulate invalid opcode */

		/* Only allow emulation of specific instructions on #UD

		 * (namely VMMCALL, sysenter, sysexit, syscall)*/

		c = &vcpu->arch.emulate_ctxt.decode;

		if ((emulation_type & EMULTYPE_TRAP_UD) &&

		    (!(c->twobyte && c->b == 0x01 &&

		      (c->modrm_reg == 0 || c->modrm_reg == 3) &&

		       c->modrm_mod == 3 && c->modrm_rm == 1)))

		if (emulation_type & EMULTYPE_TRAP_UD) {

			if (!c->twobyte)

				return EMULATE_FAIL;

			switch (c->b) {

			case 0x01: /* VMMCALL */

				if (c->modrm_mod != 3 || c->modrm_rm != 1)

					return EMULATE_FAIL;

				break;

			case 0x34: /* sysenter */

			case 0x35: /* sysexit */

				if (c->modrm_mod != 0 || c->modrm_rm != 0)

					return EMULATE_FAIL;

				break;

			case 0x05: /* syscall */

				if (c->modrm_mod != 0 || c->modrm_rm != 0)

					return EMULATE_FAIL;

				break;

			default:

				return EMULATE_FAIL;

			}



			if (!(c->modrm_reg == 0 || c->modrm_reg == 3))

				return EMULATE_FAIL;

		}



		++vcpu->stat.insn_emulation;

		if (r)  {

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