Commit 36d546d5 authored by Hou Wenlong's avatar Hou Wenlong Committed by Paolo Bonzini
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KVM: x86: Return emulator error if RDMSR/WRMSR emulation failed 



The return value of emulator_{get|set}_mst_with_filter() is confused,
since msr access error and emulator error are mixed. Although,
KVM_MSR_RET_* doesn't conflict with X86EMUL_IO_NEEDED at present, it is
better to convert msr access error to emulator error if error value is
needed.

So move "r < 0" handling for wrmsr emulation into the set helper function,
then only X86EMUL_* is returned in the helper functions. Also add "r < 0"
check in the get helper function, although KVM doesn't return -errno
today, but assuming that will always hold true is unnecessarily risking.

Suggested-by: default avatarSean Christopherson <seanjc@google.com>
Signed-off-by: default avatarHou Wenlong <houwenlong.hwl@antgroup.com>
Link: https://lore.kernel.org/r/09b2847fc3bcb8937fb11738f0ccf7be7f61d9dd.1661930557.git.houwenlong.hwl@antgroup.com


[sean: wrap changelog less aggressively]
Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent b85a97b8

arch/x86/kvm/emulate.c

+8 −12
Original line number Diff line number Diff line
@@ -3647,13 +3647,10 @@ static int em_wrmsr(struct x86_emulate_ctxt *ctxt) 
		| ((u64)reg_read(ctxt, VCPU_REGS_RDX) << 32);

	r = ctxt->ops->set_msr_with_filter(ctxt, msr_index, msr_data);



	if (r == X86EMUL_IO_NEEDED)

		return r;



	if (r > 0)

	if (r == X86EMUL_PROPAGATE_FAULT)

		return emulate_gp(ctxt, 0);



	return r < 0 ? X86EMUL_UNHANDLEABLE : X86EMUL_CONTINUE;

	return r;

}



static int em_rdmsr(struct x86_emulate_ctxt *ctxt)
@@ -3664,15 +3661,14 @@ static int em_rdmsr(struct x86_emulate_ctxt *ctxt) 


	r = ctxt->ops->get_msr_with_filter(ctxt, msr_index, &msr_data);



	if (r == X86EMUL_IO_NEEDED)

		return r;



	if (r)

	if (r == X86EMUL_PROPAGATE_FAULT)

		return emulate_gp(ctxt, 0);



	if (r == X86EMUL_CONTINUE) {

		*reg_write(ctxt, VCPU_REGS_RAX) = (u32)msr_data;

		*reg_write(ctxt, VCPU_REGS_RDX) = msr_data >> 32;

	return X86EMUL_CONTINUE;

	}

	return r;

}



static int em_store_sreg(struct x86_emulate_ctxt *ctxt, int segment)

arch/x86/kvm/x86.c

+16 −10
Original line number Diff line number Diff line
@@ -7920,14 +7920,17 @@ static int emulator_get_msr_with_filter(struct x86_emulate_ctxt *ctxt, 
	int r;



	r = kvm_get_msr_with_filter(vcpu, msr_index, pdata);

	if (r < 0)

		return X86EMUL_UNHANDLEABLE;



	if (r && kvm_msr_user_space(vcpu, msr_index, KVM_EXIT_X86_RDMSR, 0,

				    complete_emulated_rdmsr, r)) {

		/* Bounce to user space */

	if (r) {

		if (kvm_msr_user_space(vcpu, msr_index, KVM_EXIT_X86_RDMSR, 0,

				       complete_emulated_rdmsr, r))

			return X86EMUL_IO_NEEDED;

		return X86EMUL_PROPAGATE_FAULT;

	}



	return r;

	return X86EMUL_CONTINUE;

}



static int emulator_set_msr_with_filter(struct x86_emulate_ctxt *ctxt,
@@ -7937,14 +7940,17 @@ static int emulator_set_msr_with_filter(struct x86_emulate_ctxt *ctxt, 
	int r;



	r = kvm_set_msr_with_filter(vcpu, msr_index, data);

	if (r < 0)

		return X86EMUL_UNHANDLEABLE;



	if (r && kvm_msr_user_space(vcpu, msr_index, KVM_EXIT_X86_WRMSR, data,

				    complete_emulated_msr_access, r)) {

		/* Bounce to user space */

	if (r) {

		if (kvm_msr_user_space(vcpu, msr_index, KVM_EXIT_X86_WRMSR, data,

				       complete_emulated_msr_access, r))

			return X86EMUL_IO_NEEDED;

		return X86EMUL_PROPAGATE_FAULT;

	}



	return r;

	return X86EMUL_CONTINUE;

}



static int emulator_get_msr(struct x86_emulate_ctxt *ctxt,