[8/9] KVM: s390: Do not report unusabled IDs via KVM_CAP_MAX_VCPU_ID
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Message ID 20190523164309.13345-9-thuth@redhat.com
State New
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Series
  • KVM selftests for s390x
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Commit Message

Thomas Huth May 23, 2019, 4:43 p.m. UTC
KVM_CAP_MAX_VCPU_ID is currently always reporting KVM_MAX_VCPU_ID on all
architectures. However, on s390x, the amount of usable CPUs is determined
during runtime - it is depending on the features of the machine the code
is running on. Since we are using the vcpu_id as an index into the SCA
structures that are defined by the hardware (see e.g. the sca_add_vcpu()
function), it is not only the amount of CPUs that is limited by the hard-
ware, but also the range of IDs that we can use.
Thus KVM_CAP_MAX_VCPU_ID must be determined during runtime on s390x, too.
So the handling of KVM_CAP_MAX_VCPU_ID has to be moved from the common
code into the architecture specific code, and on s390x we have to return
the same value here as for KVM_CAP_MAX_VCPUS.
This problem has been discovered with the kvm_create_max_vcpus selftest.
With this change applied, the selftest now passes on s390x, too.

Signed-off-by: Thomas Huth <thuth@redhat.com>
---
 arch/mips/kvm/mips.c       | 3 +++
 arch/powerpc/kvm/powerpc.c | 3 +++
 arch/s390/kvm/kvm-s390.c   | 1 +
 arch/x86/kvm/x86.c         | 3 +++
 virt/kvm/arm/arm.c         | 3 +++
 virt/kvm/kvm_main.c        | 2 --
 6 files changed, 13 insertions(+), 2 deletions(-)

Comments

Andrew Jones May 23, 2019, 5:56 p.m. UTC | #1
On Thu, May 23, 2019 at 06:43:08PM +0200, Thomas Huth wrote:
> KVM_CAP_MAX_VCPU_ID is currently always reporting KVM_MAX_VCPU_ID on all
> architectures. However, on s390x, the amount of usable CPUs is determined
> during runtime - it is depending on the features of the machine the code
> is running on. Since we are using the vcpu_id as an index into the SCA
> structures that are defined by the hardware (see e.g. the sca_add_vcpu()
> function), it is not only the amount of CPUs that is limited by the hard-
> ware, but also the range of IDs that we can use.
> Thus KVM_CAP_MAX_VCPU_ID must be determined during runtime on s390x, too.
> So the handling of KVM_CAP_MAX_VCPU_ID has to be moved from the common
> code into the architecture specific code, and on s390x we have to return
> the same value here as for KVM_CAP_MAX_VCPUS.
> This problem has been discovered with the kvm_create_max_vcpus selftest.
> With this change applied, the selftest now passes on s390x, too.
> 
> Signed-off-by: Thomas Huth <thuth@redhat.com>
> ---
>  arch/mips/kvm/mips.c       | 3 +++
>  arch/powerpc/kvm/powerpc.c | 3 +++
>  arch/s390/kvm/kvm-s390.c   | 1 +
>  arch/x86/kvm/x86.c         | 3 +++
>  virt/kvm/arm/arm.c         | 3 +++
>  virt/kvm/kvm_main.c        | 2 --
>  6 files changed, 13 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/mips/kvm/mips.c b/arch/mips/kvm/mips.c
> index 6d0517ac18e5..0369f26ab96d 100644
> --- a/arch/mips/kvm/mips.c
> +++ b/arch/mips/kvm/mips.c
> @@ -1122,6 +1122,9 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
>  	case KVM_CAP_MAX_VCPUS:
>  		r = KVM_MAX_VCPUS;
>  		break;
> +	case KVM_CAP_MAX_VCPU_ID:
> +		r = KVM_MAX_VCPU_ID;
> +		break;
>  	case KVM_CAP_MIPS_FPU:
>  		/* We don't handle systems with inconsistent cpu_has_fpu */
>  		r = !!raw_cpu_has_fpu;
> diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
> index 3393b166817a..aa3a678711be 100644
> --- a/arch/powerpc/kvm/powerpc.c
> +++ b/arch/powerpc/kvm/powerpc.c
> @@ -657,6 +657,9 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
>  	case KVM_CAP_MAX_VCPUS:
>  		r = KVM_MAX_VCPUS;
>  		break;
> +	case KVM_CAP_MAX_VCPU_ID:
> +		r = KVM_MAX_VCPU_ID;
> +		break;
>  #ifdef CONFIG_PPC_BOOK3S_64
>  	case KVM_CAP_PPC_GET_SMMU_INFO:
>  		r = 1;
> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> index 8d6d75db8de6..871d2e99b156 100644
> --- a/arch/s390/kvm/kvm-s390.c
> +++ b/arch/s390/kvm/kvm-s390.c
> @@ -539,6 +539,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
>  		break;
>  	case KVM_CAP_NR_VCPUS:
>  	case KVM_CAP_MAX_VCPUS:
> +	case KVM_CAP_MAX_VCPU_ID:
>  		r = KVM_S390_BSCA_CPU_SLOTS;
>  		if (!kvm_s390_use_sca_entries())
>  			r = KVM_MAX_VCPUS;
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 536b78c4af6e..09a07d6a154e 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -3122,6 +3122,9 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
>  	case KVM_CAP_MAX_VCPUS:
>  		r = KVM_MAX_VCPUS;
>  		break;
> +	case KVM_CAP_MAX_VCPU_ID:
> +		r = KVM_MAX_VCPU_ID;
> +		break;
>  	case KVM_CAP_PV_MMU:	/* obsolete */
>  		r = 0;
>  		break;
> diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c
> index 90cedebaeb94..7eeebe5e9da2 100644
> --- a/virt/kvm/arm/arm.c
> +++ b/virt/kvm/arm/arm.c
> @@ -224,6 +224,9 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
>  	case KVM_CAP_MAX_VCPUS:
>  		r = KVM_MAX_VCPUS;
>  		break;
> +	case KVM_CAP_MAX_VCPU_ID:
> +		r = KVM_MAX_VCPU_ID;
> +		break;
>  	case KVM_CAP_MSI_DEVID:
>  		if (!kvm)
>  			r = -EINVAL;
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index f0d13d9d125d..c09259dd6286 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -3146,8 +3146,6 @@ static long kvm_vm_ioctl_check_extension_generic(struct kvm *kvm, long arg)
>  	case KVM_CAP_MULTI_ADDRESS_SPACE:
>  		return KVM_ADDRESS_SPACE_NUM;
>  #endif
> -	case KVM_CAP_MAX_VCPU_ID:
> -		return KVM_MAX_VCPU_ID;
>  	case KVM_CAP_NR_MEMSLOTS:
>  		return KVM_USER_MEM_SLOTS;
>  	default:
> -- 
> 2.21.0
>

Reviewed-by: Andrew Jones <drjones@redhat.com>
Cornelia Huck May 24, 2019, 9:13 a.m. UTC | #2
On Thu, 23 May 2019 18:43:08 +0200
Thomas Huth <thuth@redhat.com> wrote:

In the subject: s/unusabled/unusable/

> KVM_CAP_MAX_VCPU_ID is currently always reporting KVM_MAX_VCPU_ID on all
> architectures. However, on s390x, the amount of usable CPUs is determined
> during runtime - it is depending on the features of the machine the code
> is running on. Since we are using the vcpu_id as an index into the SCA
> structures that are defined by the hardware (see e.g. the sca_add_vcpu()
> function), it is not only the amount of CPUs that is limited by the hard-
> ware, but also the range of IDs that we can use.
> Thus KVM_CAP_MAX_VCPU_ID must be determined during runtime on s390x, too.
> So the handling of KVM_CAP_MAX_VCPU_ID has to be moved from the common
> code into the architecture specific code, and on s390x we have to return
> the same value here as for KVM_CAP_MAX_VCPUS.
> This problem has been discovered with the kvm_create_max_vcpus selftest.
> With this change applied, the selftest now passes on s390x, too.
> 
> Signed-off-by: Thomas Huth <thuth@redhat.com>
> ---
>  arch/mips/kvm/mips.c       | 3 +++
>  arch/powerpc/kvm/powerpc.c | 3 +++
>  arch/s390/kvm/kvm-s390.c   | 1 +
>  arch/x86/kvm/x86.c         | 3 +++
>  virt/kvm/arm/arm.c         | 3 +++
>  virt/kvm/kvm_main.c        | 2 --
>  6 files changed, 13 insertions(+), 2 deletions(-)

Reviewed-by: Cornelia Huck <cohuck@redhat.com>
David Hildenbrand May 24, 2019, 9:16 a.m. UTC | #3
On 23.05.19 18:43, Thomas Huth wrote:
> KVM_CAP_MAX_VCPU_ID is currently always reporting KVM_MAX_VCPU_ID on all
> architectures. However, on s390x, the amount of usable CPUs is determined
> during runtime - it is depending on the features of the machine the code
> is running on. Since we are using the vcpu_id as an index into the SCA
> structures that are defined by the hardware (see e.g. the sca_add_vcpu()
> function), it is not only the amount of CPUs that is limited by the hard-
> ware, but also the range of IDs that we can use.
> Thus KVM_CAP_MAX_VCPU_ID must be determined during runtime on s390x, too.
> So the handling of KVM_CAP_MAX_VCPU_ID has to be moved from the common
> code into the architecture specific code, and on s390x we have to return
> the same value here as for KVM_CAP_MAX_VCPUS.
> This problem has been discovered with the kvm_create_max_vcpus selftest.
> With this change applied, the selftest now passes on s390x, too.
> 
> Signed-off-by: Thomas Huth <thuth@redhat.com>
> ---
>  arch/mips/kvm/mips.c       | 3 +++
>  arch/powerpc/kvm/powerpc.c | 3 +++
>  arch/s390/kvm/kvm-s390.c   | 1 +
>  arch/x86/kvm/x86.c         | 3 +++
>  virt/kvm/arm/arm.c         | 3 +++
>  virt/kvm/kvm_main.c        | 2 --
>  6 files changed, 13 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/mips/kvm/mips.c b/arch/mips/kvm/mips.c
> index 6d0517ac18e5..0369f26ab96d 100644
> --- a/arch/mips/kvm/mips.c
> +++ b/arch/mips/kvm/mips.c
> @@ -1122,6 +1122,9 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
>  	case KVM_CAP_MAX_VCPUS:
>  		r = KVM_MAX_VCPUS;
>  		break;
> +	case KVM_CAP_MAX_VCPU_ID:
> +		r = KVM_MAX_VCPU_ID;
> +		break;
>  	case KVM_CAP_MIPS_FPU:
>  		/* We don't handle systems with inconsistent cpu_has_fpu */
>  		r = !!raw_cpu_has_fpu;
> diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
> index 3393b166817a..aa3a678711be 100644
> --- a/arch/powerpc/kvm/powerpc.c
> +++ b/arch/powerpc/kvm/powerpc.c
> @@ -657,6 +657,9 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
>  	case KVM_CAP_MAX_VCPUS:
>  		r = KVM_MAX_VCPUS;
>  		break;
> +	case KVM_CAP_MAX_VCPU_ID:
> +		r = KVM_MAX_VCPU_ID;
> +		break;
>  #ifdef CONFIG_PPC_BOOK3S_64
>  	case KVM_CAP_PPC_GET_SMMU_INFO:
>  		r = 1;
> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> index 8d6d75db8de6..871d2e99b156 100644
> --- a/arch/s390/kvm/kvm-s390.c
> +++ b/arch/s390/kvm/kvm-s390.c
> @@ -539,6 +539,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
>  		break;
>  	case KVM_CAP_NR_VCPUS:
>  	case KVM_CAP_MAX_VCPUS:
> +	case KVM_CAP_MAX_VCPU_ID:
>  		r = KVM_S390_BSCA_CPU_SLOTS;
>  		if (!kvm_s390_use_sca_entries())
>  			r = KVM_MAX_VCPUS;
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 536b78c4af6e..09a07d6a154e 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -3122,6 +3122,9 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
>  	case KVM_CAP_MAX_VCPUS:
>  		r = KVM_MAX_VCPUS;
>  		break;
> +	case KVM_CAP_MAX_VCPU_ID:
> +		r = KVM_MAX_VCPU_ID;
> +		break;
>  	case KVM_CAP_PV_MMU:	/* obsolete */
>  		r = 0;
>  		break;
> diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c
> index 90cedebaeb94..7eeebe5e9da2 100644
> --- a/virt/kvm/arm/arm.c
> +++ b/virt/kvm/arm/arm.c
> @@ -224,6 +224,9 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
>  	case KVM_CAP_MAX_VCPUS:
>  		r = KVM_MAX_VCPUS;
>  		break;
> +	case KVM_CAP_MAX_VCPU_ID:
> +		r = KVM_MAX_VCPU_ID;
> +		break;
>  	case KVM_CAP_MSI_DEVID:
>  		if (!kvm)
>  			r = -EINVAL;
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index f0d13d9d125d..c09259dd6286 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -3146,8 +3146,6 @@ static long kvm_vm_ioctl_check_extension_generic(struct kvm *kvm, long arg)
>  	case KVM_CAP_MULTI_ADDRESS_SPACE:
>  		return KVM_ADDRESS_SPACE_NUM;
>  #endif
> -	case KVM_CAP_MAX_VCPU_ID:
> -		return KVM_MAX_VCPU_ID;
>  	case KVM_CAP_NR_MEMSLOTS:
>  		return KVM_USER_MEM_SLOTS;
>  	default:
> 

Reviewed-by: David Hildenbrand <david@redhat.com>
Christian Borntraeger May 28, 2019, 11 a.m. UTC | #4
Paolo, Radim,

would you consider this patch (or the full series) as 5.2 material or 5.3 material?


On 23.05.19 18:43, Thomas Huth wrote:
> KVM_CAP_MAX_VCPU_ID is currently always reporting KVM_MAX_VCPU_ID on all
> architectures. However, on s390x, the amount of usable CPUs is determined
> during runtime - it is depending on the features of the machine the code
> is running on. Since we are using the vcpu_id as an index into the SCA
> structures that are defined by the hardware (see e.g. the sca_add_vcpu()
> function), it is not only the amount of CPUs that is limited by the hard-
> ware, but also the range of IDs that we can use.
> Thus KVM_CAP_MAX_VCPU_ID must be determined during runtime on s390x, too.
> So the handling of KVM_CAP_MAX_VCPU_ID has to be moved from the common
> code into the architecture specific code, and on s390x we have to return
> the same value here as for KVM_CAP_MAX_VCPUS.
> This problem has been discovered with the kvm_create_max_vcpus selftest.
> With this change applied, the selftest now passes on s390x, too.
> 
> Signed-off-by: Thomas Huth <thuth@redhat.com>
> ---
>  arch/mips/kvm/mips.c       | 3 +++
>  arch/powerpc/kvm/powerpc.c | 3 +++
>  arch/s390/kvm/kvm-s390.c   | 1 +
>  arch/x86/kvm/x86.c         | 3 +++
>  virt/kvm/arm/arm.c         | 3 +++
>  virt/kvm/kvm_main.c        | 2 --
>  6 files changed, 13 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/mips/kvm/mips.c b/arch/mips/kvm/mips.c
> index 6d0517ac18e5..0369f26ab96d 100644
> --- a/arch/mips/kvm/mips.c
> +++ b/arch/mips/kvm/mips.c
> @@ -1122,6 +1122,9 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
>  	case KVM_CAP_MAX_VCPUS:
>  		r = KVM_MAX_VCPUS;
>  		break;
> +	case KVM_CAP_MAX_VCPU_ID:
> +		r = KVM_MAX_VCPU_ID;
> +		break;
>  	case KVM_CAP_MIPS_FPU:
>  		/* We don't handle systems with inconsistent cpu_has_fpu */
>  		r = !!raw_cpu_has_fpu;
> diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
> index 3393b166817a..aa3a678711be 100644
> --- a/arch/powerpc/kvm/powerpc.c
> +++ b/arch/powerpc/kvm/powerpc.c
> @@ -657,6 +657,9 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
>  	case KVM_CAP_MAX_VCPUS:
>  		r = KVM_MAX_VCPUS;
>  		break;
> +	case KVM_CAP_MAX_VCPU_ID:
> +		r = KVM_MAX_VCPU_ID;
> +		break;
>  #ifdef CONFIG_PPC_BOOK3S_64
>  	case KVM_CAP_PPC_GET_SMMU_INFO:
>  		r = 1;
> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> index 8d6d75db8de6..871d2e99b156 100644
> --- a/arch/s390/kvm/kvm-s390.c
> +++ b/arch/s390/kvm/kvm-s390.c
> @@ -539,6 +539,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
>  		break;
>  	case KVM_CAP_NR_VCPUS:
>  	case KVM_CAP_MAX_VCPUS:
> +	case KVM_CAP_MAX_VCPU_ID:
>  		r = KVM_S390_BSCA_CPU_SLOTS;
>  		if (!kvm_s390_use_sca_entries())
>  			r = KVM_MAX_VCPUS;
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 536b78c4af6e..09a07d6a154e 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -3122,6 +3122,9 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
>  	case KVM_CAP_MAX_VCPUS:
>  		r = KVM_MAX_VCPUS;
>  		break;
> +	case KVM_CAP_MAX_VCPU_ID:
> +		r = KVM_MAX_VCPU_ID;
> +		break;
>  	case KVM_CAP_PV_MMU:	/* obsolete */
>  		r = 0;
>  		break;
> diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c
> index 90cedebaeb94..7eeebe5e9da2 100644
> --- a/virt/kvm/arm/arm.c
> +++ b/virt/kvm/arm/arm.c
> @@ -224,6 +224,9 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
>  	case KVM_CAP_MAX_VCPUS:
>  		r = KVM_MAX_VCPUS;
>  		break;
> +	case KVM_CAP_MAX_VCPU_ID:
> +		r = KVM_MAX_VCPU_ID;
> +		break;
>  	case KVM_CAP_MSI_DEVID:
>  		if (!kvm)
>  			r = -EINVAL;
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index f0d13d9d125d..c09259dd6286 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -3146,8 +3146,6 @@ static long kvm_vm_ioctl_check_extension_generic(struct kvm *kvm, long arg)
>  	case KVM_CAP_MULTI_ADDRESS_SPACE:
>  		return KVM_ADDRESS_SPACE_NUM;
>  #endif
> -	case KVM_CAP_MAX_VCPU_ID:
> -		return KVM_MAX_VCPU_ID;
>  	case KVM_CAP_NR_MEMSLOTS:
>  		return KVM_USER_MEM_SLOTS;
>  	default:
>
Cornelia Huck May 28, 2019, 12:53 p.m. UTC | #5
On Tue, 28 May 2019 13:00:30 +0200
Christian Borntraeger <borntraeger@de.ibm.com> wrote:

> Paolo, Radim,
> 
> would you consider this patch (or the full series) as 5.2 material or 5.3 material?

FWIW, I'd consider this patch 5.2 material, as we're currently relaying
wrong values to userspace.

> 
> 
> On 23.05.19 18:43, Thomas Huth wrote:
> > KVM_CAP_MAX_VCPU_ID is currently always reporting KVM_MAX_VCPU_ID on all
> > architectures. However, on s390x, the amount of usable CPUs is determined
> > during runtime - it is depending on the features of the machine the code
> > is running on. Since we are using the vcpu_id as an index into the SCA
> > structures that are defined by the hardware (see e.g. the sca_add_vcpu()
> > function), it is not only the amount of CPUs that is limited by the hard-
> > ware, but also the range of IDs that we can use.
> > Thus KVM_CAP_MAX_VCPU_ID must be determined during runtime on s390x, too.
> > So the handling of KVM_CAP_MAX_VCPU_ID has to be moved from the common
> > code into the architecture specific code, and on s390x we have to return
> > the same value here as for KVM_CAP_MAX_VCPUS.
> > This problem has been discovered with the kvm_create_max_vcpus selftest.
> > With this change applied, the selftest now passes on s390x, too.
> > 
> > Signed-off-by: Thomas Huth <thuth@redhat.com>
> > ---
> >  arch/mips/kvm/mips.c       | 3 +++
> >  arch/powerpc/kvm/powerpc.c | 3 +++
> >  arch/s390/kvm/kvm-s390.c   | 1 +
> >  arch/x86/kvm/x86.c         | 3 +++
> >  virt/kvm/arm/arm.c         | 3 +++
> >  virt/kvm/kvm_main.c        | 2 --
> >  6 files changed, 13 insertions(+), 2 deletions(-)
Christian Borntraeger May 28, 2019, 1:48 p.m. UTC | #6
On 28.05.19 14:53, Cornelia Huck wrote:
> On Tue, 28 May 2019 13:00:30 +0200
> Christian Borntraeger <borntraeger@de.ibm.com> wrote:
> 
>> Paolo, Radim,
>>
>> would you consider this patch (or the full series) as 5.2 material or 5.3 material?
> 
> FWIW, I'd consider this patch 5.2 material, as we're currently relaying
> wrong values to userspace.

Agreed. I will add cc stable and queue for master. What is our opinion about kselftest?
Are we merging testtools changes also only during the merge window?
> 
>>
>>
>> On 23.05.19 18:43, Thomas Huth wrote:
>>> KVM_CAP_MAX_VCPU_ID is currently always reporting KVM_MAX_VCPU_ID on all
>>> architectures. However, on s390x, the amount of usable CPUs is determined
>>> during runtime - it is depending on the features of the machine the code
>>> is running on. Since we are using the vcpu_id as an index into the SCA
>>> structures that are defined by the hardware (see e.g. the sca_add_vcpu()
>>> function), it is not only the amount of CPUs that is limited by the hard-
>>> ware, but also the range of IDs that we can use.
>>> Thus KVM_CAP_MAX_VCPU_ID must be determined during runtime on s390x, too.
>>> So the handling of KVM_CAP_MAX_VCPU_ID has to be moved from the common
>>> code into the architecture specific code, and on s390x we have to return
>>> the same value here as for KVM_CAP_MAX_VCPUS.
>>> This problem has been discovered with the kvm_create_max_vcpus selftest.
>>> With this change applied, the selftest now passes on s390x, too.
>>>
>>> Signed-off-by: Thomas Huth <thuth@redhat.com>
>>> ---
>>>  arch/mips/kvm/mips.c       | 3 +++
>>>  arch/powerpc/kvm/powerpc.c | 3 +++
>>>  arch/s390/kvm/kvm-s390.c   | 1 +
>>>  arch/x86/kvm/x86.c         | 3 +++
>>>  virt/kvm/arm/arm.c         | 3 +++
>>>  virt/kvm/kvm_main.c        | 2 --
>>>  6 files changed, 13 insertions(+), 2 deletions(-)
>

Patch
diff mbox series

diff --git a/arch/mips/kvm/mips.c b/arch/mips/kvm/mips.c
index 6d0517ac18e5..0369f26ab96d 100644
--- a/arch/mips/kvm/mips.c
+++ b/arch/mips/kvm/mips.c
@@ -1122,6 +1122,9 @@  int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
 	case KVM_CAP_MAX_VCPUS:
 		r = KVM_MAX_VCPUS;
 		break;
+	case KVM_CAP_MAX_VCPU_ID:
+		r = KVM_MAX_VCPU_ID;
+		break;
 	case KVM_CAP_MIPS_FPU:
 		/* We don't handle systems with inconsistent cpu_has_fpu */
 		r = !!raw_cpu_has_fpu;
diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
index 3393b166817a..aa3a678711be 100644
--- a/arch/powerpc/kvm/powerpc.c
+++ b/arch/powerpc/kvm/powerpc.c
@@ -657,6 +657,9 @@  int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
 	case KVM_CAP_MAX_VCPUS:
 		r = KVM_MAX_VCPUS;
 		break;
+	case KVM_CAP_MAX_VCPU_ID:
+		r = KVM_MAX_VCPU_ID;
+		break;
 #ifdef CONFIG_PPC_BOOK3S_64
 	case KVM_CAP_PPC_GET_SMMU_INFO:
 		r = 1;
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 8d6d75db8de6..871d2e99b156 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -539,6 +539,7 @@  int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
 		break;
 	case KVM_CAP_NR_VCPUS:
 	case KVM_CAP_MAX_VCPUS:
+	case KVM_CAP_MAX_VCPU_ID:
 		r = KVM_S390_BSCA_CPU_SLOTS;
 		if (!kvm_s390_use_sca_entries())
 			r = KVM_MAX_VCPUS;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 536b78c4af6e..09a07d6a154e 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3122,6 +3122,9 @@  int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
 	case KVM_CAP_MAX_VCPUS:
 		r = KVM_MAX_VCPUS;
 		break;
+	case KVM_CAP_MAX_VCPU_ID:
+		r = KVM_MAX_VCPU_ID;
+		break;
 	case KVM_CAP_PV_MMU:	/* obsolete */
 		r = 0;
 		break;
diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c
index 90cedebaeb94..7eeebe5e9da2 100644
--- a/virt/kvm/arm/arm.c
+++ b/virt/kvm/arm/arm.c
@@ -224,6 +224,9 @@  int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
 	case KVM_CAP_MAX_VCPUS:
 		r = KVM_MAX_VCPUS;
 		break;
+	case KVM_CAP_MAX_VCPU_ID:
+		r = KVM_MAX_VCPU_ID;
+		break;
 	case KVM_CAP_MSI_DEVID:
 		if (!kvm)
 			r = -EINVAL;
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index f0d13d9d125d..c09259dd6286 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -3146,8 +3146,6 @@  static long kvm_vm_ioctl_check_extension_generic(struct kvm *kvm, long arg)
 	case KVM_CAP_MULTI_ADDRESS_SPACE:
 		return KVM_ADDRESS_SPACE_NUM;
 #endif
-	case KVM_CAP_MAX_VCPU_ID:
-		return KVM_MAX_VCPU_ID;
 	case KVM_CAP_NR_MEMSLOTS:
 		return KVM_USER_MEM_SLOTS;
 	default: