linux-kernel - [PATCH] KVM: x86: do not use KVM_X86_OP_OPTIONAL_RET0 for get_mt

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Date:   Fri, 18 Mar 2022 12:29:37 -0400
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     mlevitsk@...hat.com
Subject: [PATCH] KVM: x86: do not use KVM_X86_OP_OPTIONAL_RET0 for get_mt_mask

From: Maxim Levitsky <mlevitsk@...hat.com>

KVM_X86_OP_OPTIONAL_RET0 can only be used with 32-bit return values on 32-bit
systems, because unsigned long is only 32-bits wide there and 64-bit values
are returned in edx:eax.

Reported-by: Maxim Levitsky <mlevitsk@...hat.com>
Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
---
 arch/x86/include/asm/kvm-x86-ops.h | 2 +-
 arch/x86/kvm/svm/svm.c             | 6 ++++++
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/kvm-x86-ops.h b/arch/x86/include/asm/kvm-x86-ops.h
index 29affccb353c..3c368b639c04 100644
--- a/arch/x86/include/asm/kvm-x86-ops.h
+++ b/arch/x86/include/asm/kvm-x86-ops.h
@@ -87,7 +87,7 @@ KVM_X86_OP(deliver_interrupt)
 KVM_X86_OP_OPTIONAL(sync_pir_to_irr)
 KVM_X86_OP_OPTIONAL_RET0(set_tss_addr)
 KVM_X86_OP_OPTIONAL_RET0(set_identity_map_addr)
-KVM_X86_OP_OPTIONAL_RET0(get_mt_mask)
+KVM_X86_OP(get_mt_mask)
 KVM_X86_OP(load_mmu_pgd)
 KVM_X86_OP(has_wbinvd_exit)
 KVM_X86_OP(get_l2_tsc_offset)
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index fc5222a0f506..0884c3414a1b 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -3939,6 +3939,11 @@ static bool svm_has_emulated_msr(struct kvm *kvm, u32 index)
 	return true;
 }
 
+static u64 svm_get_mt_mask(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio)
+{
+	return 0;
+}
+
 static void svm_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu)
 {
 	struct vcpu_svm *svm = to_svm(vcpu);
@@ -4593,6 +4598,7 @@ static struct kvm_x86_ops svm_x86_ops __initdata = {
 	.check_apicv_inhibit_reasons = avic_check_apicv_inhibit_reasons,
 	.apicv_post_state_restore = avic_apicv_post_state_restore,
 
+	.get_mt_mask = svm_get_mt_mask,
 	.get_exit_info = svm_get_exit_info,
 
 	.vcpu_after_set_cpuid = svm_vcpu_after_set_cpuid,
-- 
2.31.1