[PATCH v2 3/5] KVM/x86: Return -errno instead of "1" for Hyper-V related MSR emulation
From: Juergen Gross
Date: Thu May 28 2026 - 07:14:35 EST
Instead of a literal "1" for signalling an error, use a negative errno
value in the emulation code of Hyper-V related MSR registers.
Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
---
V2:
- use -errno instead of KVM_MSR_RET_ERR
---
arch/x86/kvm/hyperv.c | 72 +++++++++++++++++++++----------------------
1 file changed, 36 insertions(+), 36 deletions(-)
diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index 4438ecac9a89..809752a6d0ac 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -167,7 +167,7 @@ static int synic_set_sint(struct kvm_vcpu_hv_synic *synic, int sint,
* allow zero-initing the register from host as well.
*/
if (vector < HV_SYNIC_FIRST_VALID_VECTOR && !host && !masked)
- return 1;
+ return -EINVAL;
/*
* Guest may configure multiple SINTs to use the same vector, so
* we maintain a bitmap of vectors handled by synic, and a
@@ -263,7 +263,7 @@ static int synic_set_msr(struct kvm_vcpu_hv_synic *synic,
int ret;
if (!synic->active && (!host || data))
- return 1;
+ return -EINVAL;
trace_kvm_hv_synic_set_msr(vcpu->vcpu_id, msr, data, host);
@@ -276,7 +276,7 @@ static int synic_set_msr(struct kvm_vcpu_hv_synic *synic,
break;
case HV_X64_MSR_SVERSION:
if (!host) {
- ret = 1;
+ ret = -EINVAL;
break;
}
synic->version = data;
@@ -286,7 +286,7 @@ static int synic_set_msr(struct kvm_vcpu_hv_synic *synic,
!synic->dont_zero_synic_pages)
if (kvm_clear_guest(vcpu->kvm,
data & PAGE_MASK, PAGE_SIZE)) {
- ret = 1;
+ ret = -EFAULT;
break;
}
synic->evt_page = data;
@@ -298,7 +298,7 @@ static int synic_set_msr(struct kvm_vcpu_hv_synic *synic,
!synic->dont_zero_synic_pages)
if (kvm_clear_guest(vcpu->kvm,
data & PAGE_MASK, PAGE_SIZE)) {
- ret = 1;
+ ret = -EFAULT;
break;
}
synic->msg_page = data;
@@ -319,7 +319,7 @@ static int synic_set_msr(struct kvm_vcpu_hv_synic *synic,
ret = synic_set_sint(synic, msr - HV_X64_MSR_SINT0, data, host);
break;
default:
- ret = 1;
+ ret = -EINVAL;
break;
}
return ret;
@@ -365,7 +365,7 @@ static int syndbg_set_msr(struct kvm_vcpu *vcpu, u32 msr, u64 data, bool host)
struct kvm_hv_syndbg *syndbg = to_hv_syndbg(vcpu);
if (!kvm_hv_is_syndbg_enabled(vcpu) && !host)
- return 1;
+ return -EINVAL;
trace_kvm_hv_syndbg_set_msr(vcpu->vcpu_id,
to_hv_vcpu(vcpu)->vp_index, msr, data);
@@ -404,7 +404,7 @@ static int syndbg_get_msr(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata, bool host)
struct kvm_hv_syndbg *syndbg = to_hv_syndbg(vcpu);
if (!kvm_hv_is_syndbg_enabled(vcpu) && !host)
- return 1;
+ return -EINVAL;
switch (msr) {
case HV_X64_MSR_SYNDBG_CONTROL:
@@ -440,7 +440,7 @@ static int synic_get_msr(struct kvm_vcpu_hv_synic *synic, u32 msr, u64 *pdata,
int ret;
if (!synic->active && !host)
- return 1;
+ return -EINVAL;
ret = 0;
switch (msr) {
@@ -463,7 +463,7 @@ static int synic_get_msr(struct kvm_vcpu_hv_synic *synic, u32 msr, u64 *pdata,
*pdata = atomic64_read(&synic->sint[msr - HV_X64_MSR_SINT0]);
break;
default:
- ret = 1;
+ ret = -EINVAL;
break;
}
return ret;
@@ -695,12 +695,12 @@ static int stimer_set_config(struct kvm_vcpu_hv_stimer *stimer, u64 config,
struct kvm_vcpu_hv_synic *synic = to_hv_synic(vcpu);
if (!synic->active && (!host || config))
- return 1;
+ return -EINVAL;
if (unlikely(!host && hv_vcpu->enforce_cpuid && new_config.direct_mode &&
!(hv_vcpu->cpuid_cache.features_edx &
HV_STIMER_DIRECT_MODE_AVAILABLE)))
- return 1;
+ return -EINVAL;
trace_kvm_hv_stimer_set_config(hv_stimer_to_vcpu(stimer)->vcpu_id,
stimer->index, config, host);
@@ -724,7 +724,7 @@ static int stimer_set_count(struct kvm_vcpu_hv_stimer *stimer, u64 count,
struct kvm_vcpu_hv_synic *synic = to_hv_synic(vcpu);
if (!synic->active && (!host || count))
- return 1;
+ return -EINVAL;
trace_kvm_hv_stimer_set_count(hv_stimer_to_vcpu(stimer)->vcpu_id,
stimer->index, count, host);
@@ -1380,7 +1380,7 @@ static int kvm_hv_set_msr_pw(struct kvm_vcpu *vcpu, u32 msr, u64 data,
struct kvm_hv *hv = to_kvm_hv(kvm);
if (unlikely(!host && !hv_check_msr_access(to_hv_vcpu(vcpu), msr)))
- return 1;
+ return -EINVAL;
switch (msr) {
case HV_X64_MSR_GUEST_OS_ID:
@@ -1476,23 +1476,23 @@ static int kvm_hv_set_msr_pw(struct kvm_vcpu *vcpu, u32 msr, u64 data,
break;
case HV_X64_MSR_TSC_EMULATION_STATUS:
if (data && !host)
- return 1;
+ return -EINVAL;
hv->hv_tsc_emulation_status = data;
break;
case HV_X64_MSR_TIME_REF_COUNT:
/* read-only, but still ignore it if host-initiated */
if (!host)
- return 1;
+ return -EINVAL;
break;
case HV_X64_MSR_TSC_INVARIANT_CONTROL:
/* Only bit 0 is supported */
if (data & ~HV_EXPOSE_INVARIANT_TSC)
- return 1;
+ return -EINVAL;
/* The feature can't be disabled from the guest */
if (!host && hv->hv_invtsc_control && !data)
- return 1;
+ return -EINVAL;
hv->hv_invtsc_control = data;
break;
@@ -1501,7 +1501,7 @@ static int kvm_hv_set_msr_pw(struct kvm_vcpu *vcpu, u32 msr, u64 data,
return syndbg_set_msr(vcpu, msr, data, host);
default:
kvm_pr_unimpl_wrmsr(vcpu, msr, data);
- return 1;
+ return -EINVAL;
}
return 0;
}
@@ -1521,7 +1521,7 @@ static int kvm_hv_set_msr(struct kvm_vcpu *vcpu, u32 msr, u64 data, bool host)
struct kvm_vcpu_hv *hv_vcpu = to_hv_vcpu(vcpu);
if (unlikely(!host && !hv_check_msr_access(hv_vcpu, msr)))
- return 1;
+ return -EINVAL;
switch (msr) {
case HV_X64_MSR_VP_INDEX: {
@@ -1529,7 +1529,7 @@ static int kvm_hv_set_msr(struct kvm_vcpu *vcpu, u32 msr, u64 data, bool host)
u32 new_vp_index = (u32)data;
if (!host || new_vp_index >= KVM_MAX_VCPUS)
- return 1;
+ return -EINVAL;
if (new_vp_index == hv_vcpu->vp_index)
return 0;
@@ -1555,13 +1555,13 @@ static int kvm_hv_set_msr(struct kvm_vcpu *vcpu, u32 msr, u64 data, bool host)
if (!(data & HV_X64_MSR_VP_ASSIST_PAGE_ENABLE)) {
hv_vcpu->hv_vapic = data;
if (kvm_lapic_set_pv_eoi(vcpu, 0, 0))
- return 1;
+ return -EINVAL;
break;
}
gfn = data >> HV_X64_MSR_VP_ASSIST_PAGE_ADDRESS_SHIFT;
addr = kvm_vcpu_gfn_to_hva(vcpu, gfn);
if (kvm_is_error_hva(addr))
- return 1;
+ return -EINVAL;
/*
* Clear apic_assist portion of struct hv_vp_assist_page
@@ -1569,13 +1569,13 @@ static int kvm_hv_set_msr(struct kvm_vcpu *vcpu, u32 msr, u64 data, bool host)
* to be preserved e.g. on migration.
*/
if (put_user(0, (u32 __user *)addr))
- return 1;
+ return -EFAULT;
hv_vcpu->hv_vapic = data;
kvm_vcpu_mark_page_dirty(vcpu, gfn);
if (kvm_lapic_set_pv_eoi(vcpu,
gfn_to_gpa(gfn) | KVM_MSR_ENABLED,
sizeof(struct hv_vp_assist_page)))
- return 1;
+ return -EINVAL;
break;
}
case HV_X64_MSR_EOI:
@@ -1586,7 +1586,7 @@ static int kvm_hv_set_msr(struct kvm_vcpu *vcpu, u32 msr, u64 data, bool host)
return kvm_hv_vapic_msr_write(vcpu, APIC_TASKPRI, data);
case HV_X64_MSR_VP_RUNTIME:
if (!host)
- return 1;
+ return -EINVAL;
hv_vcpu->runtime_offset = data - current_task_runtime_100ns();
break;
case HV_X64_MSR_SCONTROL:
@@ -1618,11 +1618,11 @@ static int kvm_hv_set_msr(struct kvm_vcpu *vcpu, u32 msr, u64 data, bool host)
case HV_X64_MSR_APIC_FREQUENCY:
/* read-only, but still ignore it if host-initiated */
if (!host)
- return 1;
+ return -EINVAL;
break;
default:
kvm_pr_unimpl_wrmsr(vcpu, msr, data);
- return 1;
+ return -EINVAL;
}
return 0;
@@ -1636,7 +1636,7 @@ static int kvm_hv_get_msr_pw(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata,
struct kvm_hv *hv = to_kvm_hv(kvm);
if (unlikely(!host && !hv_check_msr_access(to_hv_vcpu(vcpu), msr)))
- return 1;
+ return -EINVAL;
switch (msr) {
case HV_X64_MSR_GUEST_OS_ID:
@@ -1677,7 +1677,7 @@ static int kvm_hv_get_msr_pw(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata,
return syndbg_get_msr(vcpu, msr, pdata, host);
default:
kvm_pr_unimpl_rdmsr(vcpu, msr);
- return 1;
+ return -EINVAL;
}
*pdata = data;
@@ -1691,7 +1691,7 @@ static int kvm_hv_get_msr(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata,
struct kvm_vcpu_hv *hv_vcpu = to_hv_vcpu(vcpu);
if (unlikely(!host && !hv_check_msr_access(hv_vcpu, msr)))
- return 1;
+ return -EINVAL;
switch (msr) {
case HV_X64_MSR_VP_INDEX:
@@ -1743,7 +1743,7 @@ static int kvm_hv_get_msr(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata,
break;
default:
kvm_pr_unimpl_rdmsr(vcpu, msr);
- return 1;
+ return -EINVAL;
}
*pdata = data;
return 0;
@@ -1754,10 +1754,10 @@ int kvm_hv_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data, bool host)
struct kvm_hv *hv = to_kvm_hv(vcpu->kvm);
if (!host && !vcpu->arch.hyperv_enabled)
- return 1;
+ return -EINVAL;
if (kvm_hv_vcpu_init(vcpu))
- return 1;
+ return -EINVAL;
if (kvm_hv_msr_partition_wide(msr)) {
int r;
@@ -1775,10 +1775,10 @@ int kvm_hv_get_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata, bool host)
struct kvm_hv *hv = to_kvm_hv(vcpu->kvm);
if (!host && !vcpu->arch.hyperv_enabled)
- return 1;
+ return -EINVAL;
if (kvm_hv_vcpu_init(vcpu))
- return 1;
+ return -EINVAL;
if (kvm_hv_msr_partition_wide(msr)) {
int r;
--
2.54.0