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Subject[PATCH v6 3/4] KVM: x86: allow kvm_x86_ops.set_efer to return an error value
Date
This will be used to signal an error to the userspace, in case
the vendor code failed during handling of this msr. (e.g -ENOMEM)

Signed-off-by: Maxim Levitsky <mlevitsk@redhat.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 | 6 ++++--
arch/x86/kvm/x86.c | 8 +++++++-
5 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 5303dbc5c9bce..b273c199b9a55 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 3da5b2f1b4a19..18f8af55e970a 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 45496775f0db2..1e1842de0efe7 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -338,7 +338,7 @@ 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 6f9a0c6d5dc59..7f7451ff80ffc 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -2835,13 +2835,14 @@ 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);

+ /* Nothing to do if hardware doesn't support EFER. */
if (!msr)
- return;
+ return 0;

vcpu->arch.efer = efer;
if (efer & EFER_LMA) {
@@ -2853,6 +2854,7 @@ 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 e4b07be450d4e..df53baa0059fe 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1456,6 +1456,7 @@ static int set_efer(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
{
u64 old_efer = vcpu->arch.efer;
u64 efer = msr_info->data;
+ int r;

if (efer & efer_reserved_bits)
return 1;
@@ -1472,7 +1473,12 @@ 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);
+ r = kvm_x86_ops.set_efer(vcpu, efer);
+
+ if (r) {
+ WARN_ON(r > 0);
+ return r;
+ }

/* Update reserved bits */
if ((efer ^ old_efer) & EFER_NX)
--
2.26.2
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