[PATCH v1] KVM: s390: interrupt: fix virtual-physical confusion for next alert GISA

[PATCH v1] KVM: s390: interrupt: fix virtual-physical confusion for next alert GISA

[Nico Boehr]

We sometimes put a virtual address in next_alert, which should always be
a physical address, since it is shared with hardware.

This currently works, because virtual and physical addresses are
the same.

Add phys_to_virt() to resolve the virtual-physical confusion.

Signed-off-by: Nico Boehr <nrb@linux.ibm.com>
---
 arch/s390/kvm/interrupt.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
index ab26aa53ee37..20743c5b000a 100644
--- a/arch/s390/kvm/interrupt.c
+++ b/arch/s390/kvm/interrupt.c
@@ -305,7 +305,7 @@ static inline u8 gisa_get_ipm_or_restore_iam(struct kvm_s390_gisa_interrupt *gi)
 
 static inline int gisa_in_alert_list(struct kvm_s390_gisa *gisa)
 {
-	return READ_ONCE(gisa->next_alert) != (u32)(u64)gisa;
+	return READ_ONCE(gisa->next_alert) != (u32)virt_to_phys(gisa);
 }
 
 static inline void gisa_set_ipm_gisc(struct kvm_s390_gisa *gisa, u32 gisc)
@@ -3167,7 +3167,7 @@ void kvm_s390_gisa_init(struct kvm *kvm)
 	hrtimer_init(&gi->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
 	gi->timer.function = gisa_vcpu_kicker;
 	memset(gi->origin, 0, sizeof(struct kvm_s390_gisa));
-	gi->origin->next_alert = (u32)(u64)gi->origin;
+	gi->origin->next_alert = (u32)virt_to_phys(gi->origin);
 	VM_EVENT(kvm, 3, "gisa 0x%pK initialized", gi->origin);
 }
 
-- 
2.39.1

Re: [PATCH v1] KVM: s390: interrupt: fix virtual-physical confusion for next alert GISA

[Janosch Frank]

On 2/23/23 17:22, Nico Boehr wrote:
> We sometimes put a virtual address in next_alert, which should always be
> a physical address, since it is shared with hardware.
> 
> This currently works, because virtual and physical addresses are
> the same.

I'd replace that with something like:

The gisa next alert address is defined as a host absolute address so 
let's use virt_to_phys() to make sure we always write an absolute 
address to this hardware structure.

This is not a bug since we're currently still running as a virtual == 
physical kernel but plan to move away from that.

> 
> Add phys_to_virt() to resolve the virtual-physical confusion.

Reviewed-by: Janosch Frank <frankja@linux.ibm.com>

> 
> Signed-off-by: Nico Boehr <nrb@linux.ibm.com>
> ---
>   arch/s390/kvm/interrupt.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
> index ab26aa53ee37..20743c5b000a 100644
> --- a/arch/s390/kvm/interrupt.c
> +++ b/arch/s390/kvm/interrupt.c
> @@ -305,7 +305,7 @@ static inline u8 gisa_get_ipm_or_restore_iam(struct kvm_s390_gisa_interrupt *gi)
>   
>   static inline int gisa_in_alert_list(struct kvm_s390_gisa *gisa)
>   {
> -	return READ_ONCE(gisa->next_alert) != (u32)(u64)gisa;
> +	return READ_ONCE(gisa->next_alert) != (u32)virt_to_phys(gisa);
>   }
>   
>   static inline void gisa_set_ipm_gisc(struct kvm_s390_gisa *gisa, u32 gisc)
> @@ -3167,7 +3167,7 @@ void kvm_s390_gisa_init(struct kvm *kvm)
>   	hrtimer_init(&gi->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
>   	gi->timer.function = gisa_vcpu_kicker;
>   	memset(gi->origin, 0, sizeof(struct kvm_s390_gisa));
> -	gi->origin->next_alert = (u32)(u64)gi->origin;
> +	gi->origin->next_alert = (u32)virt_to_phys(gi->origin);
>   	VM_EVENT(kvm, 3, "gisa 0x%pK initialized", gi->origin);
>   }
>   

Re: [PATCH v1] KVM: s390: interrupt: fix virtual-physical confusion for next alert GISA

[Michael Mueller]

On 23.02.23 17:22, Nico Boehr wrote:
> We sometimes put a virtual address in next_alert, which should always be
> a physical address, since it is shared with hardware.
> 
> This currently works, because virtual and physical addresses are
> the same.
> 
> Add phys_to_virt() to resolve the virtual-physical confusion.
> 
> Signed-off-by: Nico Boehr <nrb@linux.ibm.com>
> ---
>   arch/s390/kvm/interrupt.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
> index ab26aa53ee37..20743c5b000a 100644
> --- a/arch/s390/kvm/interrupt.c
> +++ b/arch/s390/kvm/interrupt.c
> @@ -305,7 +305,7 @@ static inline u8 gisa_get_ipm_or_restore_iam(struct kvm_s390_gisa_interrupt *gi)
>   
>   static inline int gisa_in_alert_list(struct kvm_s390_gisa *gisa)
>   {
> -	return READ_ONCE(gisa->next_alert) != (u32)(u64)gisa;
> +	return READ_ONCE(gisa->next_alert) != (u32)virt_to_phys(gisa);
>   }
>   
>   static inline void gisa_set_ipm_gisc(struct kvm_s390_gisa *gisa, u32 gisc)
> @@ -3167,7 +3167,7 @@ void kvm_s390_gisa_init(struct kvm *kvm)
>   	hrtimer_init(&gi->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
>   	gi->timer.function = gisa_vcpu_kicker;
>   	memset(gi->origin, 0, sizeof(struct kvm_s390_gisa));
> -	gi->origin->next_alert = (u32)(u64)gi->origin;
> +	gi->origin->next_alert = (u32)virt_to_phys(gi->origin);
>   	VM_EVENT(kvm, 3, "gisa 0x%pK initialized", gi->origin);
>   }
>   

Here is my

Signed-off-by: Michael Mueller <mimu@linux.ibm.com>

I ran hades tests as well. Thanks.

Re: [PATCH v1] KVM: s390: interrupt: fix virtual-physical confusion for next alert GISA

[Janosch Frank]

On 3/7/23 14:53, Michael Mueller wrote:
> 
> 
> On 23.02.23 17:22, Nico Boehr wrote:
>> We sometimes put a virtual address in next_alert, which should always be
>> a physical address, since it is shared with hardware.
>>
>> This currently works, because virtual and physical addresses are
>> the same.
>>
>> Add phys_to_virt() to resolve the virtual-physical confusion.
>>
>> Signed-off-by: Nico Boehr <nrb@linux.ibm.com>
>> ---
>>    arch/s390/kvm/interrupt.c | 4 ++--
>>    1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
>> index ab26aa53ee37..20743c5b000a 100644
>> --- a/arch/s390/kvm/interrupt.c
>> +++ b/arch/s390/kvm/interrupt.c
>> @@ -305,7 +305,7 @@ static inline u8 gisa_get_ipm_or_restore_iam(struct kvm_s390_gisa_interrupt *gi)
>>    
>>    static inline int gisa_in_alert_list(struct kvm_s390_gisa *gisa)
>>    {
>> -	return READ_ONCE(gisa->next_alert) != (u32)(u64)gisa;
>> +	return READ_ONCE(gisa->next_alert) != (u32)virt_to_phys(gisa);
>>    }
>>    
>>    static inline void gisa_set_ipm_gisc(struct kvm_s390_gisa *gisa, u32 gisc)
>> @@ -3167,7 +3167,7 @@ void kvm_s390_gisa_init(struct kvm *kvm)
>>    	hrtimer_init(&gi->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
>>    	gi->timer.function = gisa_vcpu_kicker;
>>    	memset(gi->origin, 0, sizeof(struct kvm_s390_gisa));
>> -	gi->origin->next_alert = (u32)(u64)gi->origin;
>> +	gi->origin->next_alert = (u32)virt_to_phys(gi->origin);
>>    	VM_EVENT(kvm, 3, "gisa 0x%pK initialized", gi->origin);
>>    }
>>    
> 
> Here is my
> 
> Signed-off-by: Michael Mueller <mimu@linux.ibm.com>

After a consultation with Michael I'm now a 100% sure this is a rev-by 
and not a s-o-b. I've picked the patch with his rev-by.

Re: [PATCH v1] KVM: s390: interrupt: fix virtual-physical confusion for next alert GISA

[Michael Mueller]

On 23.02.23 17:22, Nico Boehr wrote:
> We sometimes put a virtual address in next_alert, which should always be
> a physical address, since it is shared with hardware.
> 
> This currently works, because virtual and physical addresses are
> the same.
> 
> Add phys_to_virt() to resolve the virtual-physical confusion.
> 
> Signed-off-by: Nico Boehr <nrb@linux.ibm.com>
> ---
>   arch/s390/kvm/interrupt.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
> index ab26aa53ee37..20743c5b000a 100644
> --- a/arch/s390/kvm/interrupt.c
> +++ b/arch/s390/kvm/interrupt.c
> @@ -305,7 +305,7 @@ static inline u8 gisa_get_ipm_or_restore_iam(struct kvm_s390_gisa_interrupt *gi)
>   
>   static inline int gisa_in_alert_list(struct kvm_s390_gisa *gisa)
>   {
> -	return READ_ONCE(gisa->next_alert) != (u32)(u64)gisa;
> +	return READ_ONCE(gisa->next_alert) != (u32)virt_to_phys(gisa);
>   }
>   
>   static inline void gisa_set_ipm_gisc(struct kvm_s390_gisa *gisa, u32 gisc)
> @@ -3167,7 +3167,7 @@ void kvm_s390_gisa_init(struct kvm *kvm)
>   	hrtimer_init(&gi->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
>   	gi->timer.function = gisa_vcpu_kicker;
>   	memset(gi->origin, 0, sizeof(struct kvm_s390_gisa));
> -	gi->origin->next_alert = (u32)(u64)gi->origin;
> +	gi->origin->next_alert = (u32)virt_to_phys(gi->origin);
>   	VM_EVENT(kvm, 3, "gisa 0x%pK initialized", gi->origin);
>   }
>   

I ran hades tests as well. Thanks.

Here is my

Reviewed-by: Michael Mueller <mimu@linux.ibm.com>