linux-kernel - [PATCH v2 4/7] KVM: x86: allow kvm_x86_ops.set

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Message-Id: <20200820133339.372823-5-mlevitsk@redhat.com>
Date:   Thu, 20 Aug 2020 16:33:36 +0300
From:   Maxim Levitsky <mlevitsk@...hat.com>
To:     kvm@...r.kernel.org
Cc:     x86@...nel.org (maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)),
        Jim Mattson <jmattson@...gle.com>,
        Ingo Molnar <mingo@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-kernel@...r.kernel.org (open list:X86 ARCHITECTURE (32-BIT AND
        64-BIT)), "H. Peter Anvin" <hpa@...or.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Joerg Roedel <joro@...tes.org>,
        Wanpeng Li <wanpengli@...cent.com>,
        Borislav Petkov <bp@...en8.de>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Maxim Levitsky <mlevitsk@...hat.com>
Subject: [PATCH v2 4/7] KVM: x86: allow kvm_x86_ops.set_efer to return a value

This will be used later to return an error when setting this msr fails.

For VMX, it already has an error condition when EFER is
not in the shared MSR list, so return an error in this case.

Signed-off-by: Maxim Levitsky <mlevitsk@...hat.com>
---
 arch/x86/include/asm/kvm_host.h | 2 +-
 arch/x86/kvm/svm/svm.c          | 3 ++-
 arch/x86/kvm/svm/svm.h          | 2 +-
 arch/x86/kvm/vmx/vmx.c          | 5 +++--
 arch/x86/kvm/x86.c              | 3 ++-
 5 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 5ab3af7275d8..bd0519e26053 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1069,7 +1069,7 @@ struct kvm_x86_ops {
 	void (*get_cs_db_l_bits)(struct kvm_vcpu *vcpu, int *db, int *l);
 	void (*set_cr0)(struct kvm_vcpu *vcpu, unsigned long cr0);
 	int (*set_cr4)(struct kvm_vcpu *vcpu, unsigned long cr4);
-	void (*set_efer)(struct kvm_vcpu *vcpu, u64 efer);
+	int (*set_efer)(struct kvm_vcpu *vcpu, u64 efer);
 	void (*get_idt)(struct kvm_vcpu *vcpu, struct desc_ptr *dt);
 	void (*set_idt)(struct kvm_vcpu *vcpu, struct desc_ptr *dt);
 	void (*get_gdt)(struct kvm_vcpu *vcpu, struct desc_ptr *dt);
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 7bb094bf6494..f4569899361f 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -263,7 +263,7 @@ static int get_max_npt_level(void)
 #endif
 }
 
-void svm_set_efer(struct kvm_vcpu *vcpu, u64 efer)
+int svm_set_efer(struct kvm_vcpu *vcpu, u64 efer)
 {
 	struct vcpu_svm *svm = to_svm(vcpu);
 	vcpu->arch.efer = efer;
@@ -283,6 +283,7 @@ void svm_set_efer(struct kvm_vcpu *vcpu, u64 efer)
 
 	svm->vmcb->save.efer = efer | EFER_SVME;
 	vmcb_mark_dirty(svm->vmcb, VMCB_CR);
+	return 0;
 }
 
 static int is_external_interrupt(u32 info)
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index ab913468f9cb..468c58a91534 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -349,7 +349,7 @@ static inline bool gif_set(struct vcpu_svm *svm)
 #define MSR_INVALID				0xffffffffU
 
 u32 svm_msrpm_offset(u32 msr);
-void svm_set_efer(struct kvm_vcpu *vcpu, u64 efer);
+int svm_set_efer(struct kvm_vcpu *vcpu, u64 efer);
 void svm_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0);
 int svm_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4);
 void svm_flush_tlb(struct kvm_vcpu *vcpu);
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 46ba2e03a892..e90b9e68c7ea 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -2862,13 +2862,13 @@ static void enter_rmode(struct kvm_vcpu *vcpu)
 	kvm_mmu_reset_context(vcpu);
 }
 
-void vmx_set_efer(struct kvm_vcpu *vcpu, u64 efer)
+int vmx_set_efer(struct kvm_vcpu *vcpu, u64 efer)
 {
 	struct vcpu_vmx *vmx = to_vmx(vcpu);
 	struct shared_msr_entry *msr = find_msr_entry(vmx, MSR_EFER);
 
 	if (!msr)
-		return;
+		return 1;
 
 	vcpu->arch.efer = efer;
 	if (efer & EFER_LMA) {
@@ -2880,6 +2880,7 @@ void vmx_set_efer(struct kvm_vcpu *vcpu, u64 efer)
 		msr->data = efer & ~EFER_LME;
 	}
 	setup_msrs(vmx);
+	return 0;
 }
 
 #ifdef CONFIG_X86_64
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 2db369a64f29..cad5d9778a21 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1471,7 +1471,8 @@ static int set_efer(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
 	efer &= ~EFER_LMA;
 	efer |= vcpu->arch.efer & EFER_LMA;
 
-	kvm_x86_ops.set_efer(vcpu, efer);
+	if (kvm_x86_ops.set_efer(vcpu, efer))
+		return 1;
 
 	/* Update reserved bits */
 	if ((efer ^ old_efer) & EFER_NX)
-- 
2.26.2