2020-07-09 17:16:04

by Paolo Bonzini

Subject: [PATCH] KVM: nVMX: fixes for preemption timer migration

Commit 850448f35aaf ("KVM: nVMX: Fix VMX preemption timer migration",
2020-06-01) accidentally broke nVMX live migration from older version
by changing the userspace ABI. Restore it and, while at it, ensure
that vmx->nested.has_preemption_timer_deadline is always initialized
according to the KVM_STATE_VMX_PREEMPTION_TIMER_DEADLINE flag.

Cc: Makarand Sonare <[email protected]>
Fixes: 850448f35aaf ("KVM: nVMX: Fix VMX preemption timer migration")
Signed-off-by: Paolo Bonzini <[email protected]>
---
arch/x86/include/uapi/asm/kvm.h | 5 +++--
arch/x86/kvm/vmx/nested.c | 3 ++-
2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/arch/x86/include/uapi/asm/kvm.h b/arch/x86/include/uapi/asm/kvm.h
index 17c5a038f42d..0780f97c1850 100644
--- a/arch/x86/include/uapi/asm/kvm.h
+++ b/arch/x86/include/uapi/asm/kvm.h
@@ -408,14 +408,15 @@ struct kvm_vmx_nested_state_data {
};

struct kvm_vmx_nested_state_hdr {
- __u32 flags;
__u64 vmxon_pa;
__u64 vmcs12_pa;
- __u64 preemption_timer_deadline;

struct {
__u16 flags;
} smm;
+
+ __u32 flags;
+ __u64 preemption_timer_deadline;
};

struct kvm_svm_nested_state_data {
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index b26655104d4a..3fc2411edc92 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -6180,7 +6180,8 @@ static int vmx_set_nested_state(struct kvm_vcpu *vcpu,
vmx->nested.has_preemption_timer_deadline = true;
vmx->nested.preemption_timer_deadline =
kvm_state->hdr.vmx.preemption_timer_deadline;
- }
+ } else
+ vmx->nested.has_preemption_timer_deadline = false;

if (nested_vmx_check_controls(vcpu, vmcs12) ||
nested_vmx_check_host_state(vcpu, vmcs12) ||
--
2.26.2

2020-07-09 17:24:09

by Jim Mattson

Subject: Re: [PATCH] KVM: nVMX: fixes for preemption timer migration

On Thu, Jul 9, 2020 at 10:15 AM Paolo Bonzini <[email protected]> wrote:
>
> Commit 850448f35aaf ("KVM: nVMX: Fix VMX preemption timer migration",
> 2020-06-01) accidentally broke nVMX live migration from older version
> by changing the userspace ABI. Restore it and, while at it, ensure
> that vmx->nested.has_preemption_timer_deadline is always initialized
> according to the KVM_STATE_VMX_PREEMPTION_TIMER_DEADLINE flag.
>
> Cc: Makarand Sonare <[email protected]>
> Fixes: 850448f35aaf ("KVM: nVMX: Fix VMX preemption timer migration")
> Signed-off-by: Paolo Bonzini <[email protected]>
> ---
> arch/x86/include/uapi/asm/kvm.h | 5 +++--
> arch/x86/kvm/vmx/nested.c | 3 ++-
> 2 files changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/arch/x86/include/uapi/asm/kvm.h b/arch/x86/include/uapi/asm/kvm.h
> index 17c5a038f42d..0780f97c1850 100644
> --- a/arch/x86/include/uapi/asm/kvm.h
> +++ b/arch/x86/include/uapi/asm/kvm.h
> @@ -408,14 +408,15 @@ struct kvm_vmx_nested_state_data {
> };
>
> struct kvm_vmx_nested_state_hdr {
> - __u32 flags;
> __u64 vmxon_pa;
> __u64 vmcs12_pa;
> - __u64 preemption_timer_deadline;
>
> struct {
> __u16 flags;
> } smm;
> +
> + __u32 flags;
> + __u64 preemption_timer_deadline;
> };
>
> struct kvm_svm_nested_state_data {
> diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
> index b26655104d4a..3fc2411edc92 100644
> --- a/arch/x86/kvm/vmx/nested.c
> +++ b/arch/x86/kvm/vmx/nested.c
> @@ -6180,7 +6180,8 @@ static int vmx_set_nested_state(struct kvm_vcpu *vcpu,
> vmx->nested.has_preemption_timer_deadline = true;
> vmx->nested.preemption_timer_deadline =
> kvm_state->hdr.vmx.preemption_timer_deadline;
> - }
> + } else
> + vmx->nested.has_preemption_timer_deadline = false;

Doesn't the coding standard require braces around the else clause?

Reviewed-by: Jim Mattson <[email protected]>

2020-07-09 17:27:11

by Paolo Bonzini

Subject: Re: [PATCH] KVM: nVMX: fixes for preemption timer migration

On 09/07/20 19:23, Jim Mattson wrote:
> On Thu, Jul 9, 2020 at 10:15 AM Paolo Bonzini <[email protected]> wrote:
>>
>> Commit 850448f35aaf ("KVM: nVMX: Fix VMX preemption timer migration",
>> 2020-06-01) accidentally broke nVMX live migration from older version
>> by changing the userspace ABI. Restore it and, while at it, ensure
>> that vmx->nested.has_preemption_timer_deadline is always initialized
>> according to the KVM_STATE_VMX_PREEMPTION_TIMER_DEADLINE flag.
>>
>> Cc: Makarand Sonare <[email protected]>
>> Fixes: 850448f35aaf ("KVM: nVMX: Fix VMX preemption timer migration")
>> Signed-off-by: Paolo Bonzini <[email protected]>
>> ---
>> arch/x86/include/uapi/asm/kvm.h | 5 +++--
>> arch/x86/kvm/vmx/nested.c | 3 ++-
>> 2 files changed, 5 insertions(+), 3 deletions(-)
>>
>> diff --git a/arch/x86/include/uapi/asm/kvm.h b/arch/x86/include/uapi/asm/kvm.h
>> index 17c5a038f42d..0780f97c1850 100644
>> --- a/arch/x86/include/uapi/asm/kvm.h
>> +++ b/arch/x86/include/uapi/asm/kvm.h
>> @@ -408,14 +408,15 @@ struct kvm_vmx_nested_state_data {
>> };
>>
>> struct kvm_vmx_nested_state_hdr {
>> - __u32 flags;
>> __u64 vmxon_pa;
>> __u64 vmcs12_pa;
>> - __u64 preemption_timer_deadline;
>>
>> struct {
>> __u16 flags;
>> } smm;
>> +
>> + __u32 flags;
>> + __u64 preemption_timer_deadline;
>> };
>>
>> struct kvm_svm_nested_state_data {
>> diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
>> index b26655104d4a..3fc2411edc92 100644
>> --- a/arch/x86/kvm/vmx/nested.c
>> +++ b/arch/x86/kvm/vmx/nested.c
>> @@ -6180,7 +6180,8 @@ static int vmx_set_nested_state(struct kvm_vcpu *vcpu,
>> vmx->nested.has_preemption_timer_deadline = true;
>> vmx->nested.preemption_timer_deadline =
>> kvm_state->hdr.vmx.preemption_timer_deadline;
>> - }
>> + } else
>> + vmx->nested.has_preemption_timer_deadline = false;
>
> Doesn't the coding standard require braces around the else clause?

Yes, indeed.

Paolo

> Reviewed-by: Jim Mattson <[email protected]>
>

2020-07-09 17:36:56

by Bandan Das

Subject: Re: [PATCH] KVM: nVMX: fixes for preemption timer migration

Jim Mattson <[email protected]> writes:

> On Thu, Jul 9, 2020 at 10:15 AM Paolo Bonzini <[email protected]> wrote:
>>
>> Commit 850448f35aaf ("KVM: nVMX: Fix VMX preemption timer migration",
>> 2020-06-01) accidentally broke nVMX live migration from older version
>> by changing the userspace ABI. Restore it and, while at it, ensure
>> that vmx->nested.has_preemption_timer_deadline is always initialized
>> according to the KVM_STATE_VMX_PREEMPTION_TIMER_DEADLINE flag.
>>
>> Cc: Makarand Sonare <[email protected]>
>> Fixes: 850448f35aaf ("KVM: nVMX: Fix VMX preemption timer migration")
>> Signed-off-by: Paolo Bonzini <[email protected]>
>> ---
>> arch/x86/include/uapi/asm/kvm.h | 5 +++--
>> arch/x86/kvm/vmx/nested.c | 3 ++-
>> 2 files changed, 5 insertions(+), 3 deletions(-)
>>
>> diff --git a/arch/x86/include/uapi/asm/kvm.h b/arch/x86/include/uapi/asm/kvm.h
>> index 17c5a038f42d..0780f97c1850 100644
>> --- a/arch/x86/include/uapi/asm/kvm.h
>> +++ b/arch/x86/include/uapi/asm/kvm.h
>> @@ -408,14 +408,15 @@ struct kvm_vmx_nested_state_data {
>> };
>>
>> struct kvm_vmx_nested_state_hdr {
>> - __u32 flags;
>> __u64 vmxon_pa;
>> __u64 vmcs12_pa;
>> - __u64 preemption_timer_deadline;
>>
>> struct {
>> __u16 flags;
>> } smm;
>> +
>> + __u32 flags;
>> + __u64 preemption_timer_deadline;
>> };
>>
Oops!

>> struct kvm_svm_nested_state_data {
>> diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
>> index b26655104d4a..3fc2411edc92 100644
>> --- a/arch/x86/kvm/vmx/nested.c
>> +++ b/arch/x86/kvm/vmx/nested.c
>> @@ -6180,7 +6180,8 @@ static int vmx_set_nested_state(struct kvm_vcpu *vcpu,
>> vmx->nested.has_preemption_timer_deadline = true;
>> vmx->nested.preemption_timer_deadline =
>> kvm_state->hdr.vmx.preemption_timer_deadline;
>> - }
>> + } else
>> + vmx->nested.has_preemption_timer_deadline = false;
>
> Doesn't the coding standard require braces around the else clause?
>
I think so... for if/else where at least one of them is multiline.

> Reviewed-by: Jim Mattson <[email protected]>

Looks good to me,
Reviewed-by: Bandan Das <[email protected]>