| Message ID | 1553864452-15080-23-git-send-email-Dave.Martin@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: arm64: SVE guest support | expand |
On Fri, Mar 29, 2019 at 01:00:47PM +0000, Dave Martin wrote: > Some aspects of vcpu configuration may be too complex to be > completed inside KVM_ARM_VCPU_INIT. Thus, there may be a > requirement for userspace to do some additional configuration > before various other ioctls will work in a consistent way. > > In particular this will be the case for SVE, where userspace will > need to negotiate the set of vector lengths to be made available to > the guest before the vcpu becomes fully usable. > > In order to provide an explicit way for userspace to confirm that > it has finished setting up a particular vcpu feature, this patch > adds a new ioctl KVM_ARM_VCPU_FINALIZE. > > When userspace has opted into a feature that requires finalization, > typically by means of a feature flag passed to KVM_ARM_VCPU_INIT, a > matching call to KVM_ARM_VCPU_FINALIZE is now required before > KVM_RUN or KVM_GET_REG_LIST is allowed. Individual features may > impose additional restrictions where appropriate. > > No existing vcpu features are affected by this, so current > userspace implementations will continue to work exactly as before, > with no need to issue KVM_ARM_VCPU_FINALIZE. > > As implemented in this patch, KVM_ARM_VCPU_FINALIZE is currently a > placeholder: no finalizable features exist yet, so ioctl is not > required and will always yield EINVAL. Subsequent patches will add > the finalization logic to make use of this ioctl for SVE. > > No functional change for existing userspace. > > Signed-off-by: Dave Martin <Dave.Martin@arm.com> > Reviewed-by: Julien Thierry <julien.thierry@arm.com> > Tested-by: zhang.lei <zhang.lei@jp.fujitsu.com> > > --- > > Changes since v5: > > * Commit message, including subject line, rewritten. > > This patch is a rework of "KVM: arm/arm64: Add hook to finalize the > vcpu configuration". The old subject line and commit message no > longer accurately described what the patch does. However, the code > is an evolution of the previous patch rather than a wholesale > rewrite. > > * Added an explicit KVM_ARM_VCPU_FINALIZE ioctl, rather than just > providing internal hooks in the kernel to finalize the vcpu > configuration implicitly. This allows userspace to confirm exactly > when it has finished configuring the vcpu and is ready to use it. > > This results in simpler (and hopefully more maintainable) ioctl > ordering rules. > --- > arch/arm/include/asm/kvm_host.h | 4 ++++ > arch/arm64/include/asm/kvm_host.h | 4 ++++ > include/uapi/linux/kvm.h | 3 +++ > virt/kvm/arm/arm.c | 18 ++++++++++++++++++ > 4 files changed, 29 insertions(+) > > diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h > index a49ee01..e80cfc1 100644 > --- a/arch/arm/include/asm/kvm_host.h > +++ b/arch/arm/include/asm/kvm_host.h > @@ -19,6 +19,7 @@ > #ifndef __ARM_KVM_HOST_H__ > #define __ARM_KVM_HOST_H__ > > +#include <linux/errno.h> > #include <linux/types.h> > #include <linux/kvm_types.h> > #include <asm/cputype.h> > @@ -411,4 +412,7 @@ static inline int kvm_arm_setup_stage2(struct kvm *kvm, unsigned long type) > return 0; > } > > +#define kvm_arm_vcpu_finalize(vcpu, what) (-EINVAL) > +#define kvm_arm_vcpu_is_finalized(vcpu) true > + We usually use inline functions for the stubs. > #endif /* __ARM_KVM_HOST_H__ */ > diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h > index 3e89509..98658f7 100644 > --- a/arch/arm64/include/asm/kvm_host.h > +++ b/arch/arm64/include/asm/kvm_host.h > @@ -23,6 +23,7 @@ > #define __ARM64_KVM_HOST_H__ > > #include <linux/bitmap.h> > +#include <linux/errno.h> > #include <linux/types.h> > #include <linux/jump_label.h> > #include <linux/kvm_types.h> > @@ -625,4 +626,7 @@ void kvm_arch_free_vm(struct kvm *kvm); > > int kvm_arm_setup_stage2(struct kvm *kvm, unsigned long type); > > +#define kvm_arm_vcpu_finalize(vcpu, what) (-EINVAL) > +#define kvm_arm_vcpu_is_finalized(vcpu) true Same as above. > + > #endif /* __ARM64_KVM_HOST_H__ */ > diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h > index dc77a5a..c3b8e7a 100644 > --- a/include/uapi/linux/kvm.h > +++ b/include/uapi/linux/kvm.h > @@ -1441,6 +1441,9 @@ struct kvm_enc_region { > /* Available with KVM_CAP_HYPERV_CPUID */ > #define KVM_GET_SUPPORTED_HV_CPUID _IOWR(KVMIO, 0xc1, struct kvm_cpuid2) > > +/* Available with KVM_CAP_ARM_SVE */ > +#define KVM_ARM_VCPU_FINALIZE _IOW(KVMIO, 0xc2, int) > + > /* Secure Encrypted Virtualization command */ > enum sev_cmd_id { > /* Guest initialization commands */ > diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c > index c69e137..9edbf0f 100644 > --- a/virt/kvm/arm/arm.c > +++ b/virt/kvm/arm/arm.c > @@ -545,6 +545,9 @@ static int kvm_vcpu_first_run_init(struct kvm_vcpu *vcpu) > if (likely(vcpu->arch.has_run_once)) > return 0; > > + if (!kvm_arm_vcpu_is_finalized(vcpu)) > + return -EPERM; > + > vcpu->arch.has_run_once = true; > > if (likely(irqchip_in_kernel(kvm))) { > @@ -1116,6 +1119,10 @@ long kvm_arch_vcpu_ioctl(struct file *filp, > if (unlikely(!kvm_vcpu_initialized(vcpu))) > break; > > + r = -EPERM; > + if (!kvm_arm_vcpu_is_finalized(vcpu)) > + break; > + What's the rationale for using EPERM? The finalized concept is very similar to the initialized one. So why not also use ENOEXEC for it too? > r = -EFAULT; > if (copy_from_user(®_list, user_list, sizeof(reg_list))) > break; > @@ -1169,6 +1176,17 @@ long kvm_arch_vcpu_ioctl(struct file *filp, > > return kvm_arm_vcpu_set_events(vcpu, &events); > } > + case KVM_ARM_VCPU_FINALIZE: { > + int what; > + > + if (!kvm_vcpu_initialized(vcpu)) > + return -ENOEXEC; > + > + if (get_user(what, (const int __user *)argp)) > + return -EFAULT; > + > + return kvm_arm_vcpu_finalize(vcpu, what); Almost all the cases use the 'r = ...; break;' type of pattern, leaving it to the 'return r' at the end of the function. I guess that's in case at some point more stuff is added after the switch. The only cases that don't do that are the most recent ones KVM_GET/SET_VCPU_EVENTS, which should probably be changed to fit the pattern too, rather than this new ioctl following there pattern. > + } > default: > r = -EINVAL; > } > -- > 2.1.4 > Thanks, drew
On Thu, Apr 04, 2019 at 05:07:09PM +0200, Andrew Jones wrote: > On Fri, Mar 29, 2019 at 01:00:47PM +0000, Dave Martin wrote: > > Some aspects of vcpu configuration may be too complex to be > > completed inside KVM_ARM_VCPU_INIT. Thus, there may be a > > requirement for userspace to do some additional configuration > > before various other ioctls will work in a consistent way. > > > > In particular this will be the case for SVE, where userspace will > > need to negotiate the set of vector lengths to be made available to > > the guest before the vcpu becomes fully usable. > > > > In order to provide an explicit way for userspace to confirm that > > it has finished setting up a particular vcpu feature, this patch > > adds a new ioctl KVM_ARM_VCPU_FINALIZE. > > > > When userspace has opted into a feature that requires finalization, > > typically by means of a feature flag passed to KVM_ARM_VCPU_INIT, a > > matching call to KVM_ARM_VCPU_FINALIZE is now required before > > KVM_RUN or KVM_GET_REG_LIST is allowed. Individual features may > > impose additional restrictions where appropriate. > > > > No existing vcpu features are affected by this, so current > > userspace implementations will continue to work exactly as before, > > with no need to issue KVM_ARM_VCPU_FINALIZE. > > > > As implemented in this patch, KVM_ARM_VCPU_FINALIZE is currently a > > placeholder: no finalizable features exist yet, so ioctl is not > > required and will always yield EINVAL. Subsequent patches will add > > the finalization logic to make use of this ioctl for SVE. > > > > No functional change for existing userspace. > > > > Signed-off-by: Dave Martin <Dave.Martin@arm.com> > > Reviewed-by: Julien Thierry <julien.thierry@arm.com> > > Tested-by: zhang.lei <zhang.lei@jp.fujitsu.com> > > > > --- > > > > Changes since v5: > > > > * Commit message, including subject line, rewritten. > > > > This patch is a rework of "KVM: arm/arm64: Add hook to finalize the > > vcpu configuration". The old subject line and commit message no > > longer accurately described what the patch does. However, the code > > is an evolution of the previous patch rather than a wholesale > > rewrite. > > > > * Added an explicit KVM_ARM_VCPU_FINALIZE ioctl, rather than just > > providing internal hooks in the kernel to finalize the vcpu > > configuration implicitly. This allows userspace to confirm exactly > > when it has finished configuring the vcpu and is ready to use it. > > > > This results in simpler (and hopefully more maintainable) ioctl > > ordering rules. > > --- > > arch/arm/include/asm/kvm_host.h | 4 ++++ > > arch/arm64/include/asm/kvm_host.h | 4 ++++ > > include/uapi/linux/kvm.h | 3 +++ > > virt/kvm/arm/arm.c | 18 ++++++++++++++++++ > > 4 files changed, 29 insertions(+) > > > > diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h > > index a49ee01..e80cfc1 100644 > > --- a/arch/arm/include/asm/kvm_host.h > > +++ b/arch/arm/include/asm/kvm_host.h > > @@ -19,6 +19,7 @@ > > #ifndef __ARM_KVM_HOST_H__ > > #define __ARM_KVM_HOST_H__ > > > > +#include <linux/errno.h> > > #include <linux/types.h> > > #include <linux/kvm_types.h> > > #include <asm/cputype.h> > > @@ -411,4 +412,7 @@ static inline int kvm_arm_setup_stage2(struct kvm *kvm, unsigned long type) > > return 0; > > } > > > > +#define kvm_arm_vcpu_finalize(vcpu, what) (-EINVAL) > > +#define kvm_arm_vcpu_is_finalized(vcpu) true > > + > > We usually use inline functions for the stubs. I guess we could. The vcpu_has_sve() circular include problem applies here too if we put the actual function bodies here, which is why I ended up with this. Now that the bodies (for arm64) are out of line, it actually doesn't matter. > > #endif /* __ARM_KVM_HOST_H__ */ > > diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h > > index 3e89509..98658f7 100644 > > --- a/arch/arm64/include/asm/kvm_host.h > > +++ b/arch/arm64/include/asm/kvm_host.h > > @@ -23,6 +23,7 @@ > > #define __ARM64_KVM_HOST_H__ > > > > #include <linux/bitmap.h> > > +#include <linux/errno.h> > > #include <linux/types.h> > > #include <linux/jump_label.h> > > #include <linux/kvm_types.h> > > @@ -625,4 +626,7 @@ void kvm_arch_free_vm(struct kvm *kvm); > > > > int kvm_arm_setup_stage2(struct kvm *kvm, unsigned long type); > > > > +#define kvm_arm_vcpu_finalize(vcpu, what) (-EINVAL) > > +#define kvm_arm_vcpu_is_finalized(vcpu) true > > Same as above. Ditto > > + > > #endif /* __ARM64_KVM_HOST_H__ */ > > diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h > > index dc77a5a..c3b8e7a 100644 > > --- a/include/uapi/linux/kvm.h > > +++ b/include/uapi/linux/kvm.h > > @@ -1441,6 +1441,9 @@ struct kvm_enc_region { > > /* Available with KVM_CAP_HYPERV_CPUID */ > > #define KVM_GET_SUPPORTED_HV_CPUID _IOWR(KVMIO, 0xc1, struct kvm_cpuid2) > > > > +/* Available with KVM_CAP_ARM_SVE */ > > +#define KVM_ARM_VCPU_FINALIZE _IOW(KVMIO, 0xc2, int) > > + > > /* Secure Encrypted Virtualization command */ > > enum sev_cmd_id { > > /* Guest initialization commands */ > > diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c > > index c69e137..9edbf0f 100644 > > --- a/virt/kvm/arm/arm.c > > +++ b/virt/kvm/arm/arm.c > > @@ -545,6 +545,9 @@ static int kvm_vcpu_first_run_init(struct kvm_vcpu *vcpu) > > if (likely(vcpu->arch.has_run_once)) > > return 0; > > > > + if (!kvm_arm_vcpu_is_finalized(vcpu)) > > + return -EPERM; > > + > > vcpu->arch.has_run_once = true; > > > > if (likely(irqchip_in_kernel(kvm))) { > > @@ -1116,6 +1119,10 @@ long kvm_arch_vcpu_ioctl(struct file *filp, > > if (unlikely(!kvm_vcpu_initialized(vcpu))) > > break; > > > > + r = -EPERM; > > + if (!kvm_arm_vcpu_is_finalized(vcpu)) > > + break; > > + > > What's the rationale for using EPERM? The finalized concept is very > similar to the initialized one. So why not also use ENOEXEC for it too? Hmm, I guess we could equally return ENOEXEC. Initially this felt like a more distinctive case. Assuming Marc is happy to take an ABI fix into kvmarm/next, I'm can change them. We're not absolutely committed until this hits mainline... > > r = -EFAULT; > > if (copy_from_user(®_list, user_list, sizeof(reg_list))) > > break; > > @@ -1169,6 +1176,17 @@ long kvm_arch_vcpu_ioctl(struct file *filp, > > > > return kvm_arm_vcpu_set_events(vcpu, &events); > > } > > + case KVM_ARM_VCPU_FINALIZE: { > > + int what; > > + > > + if (!kvm_vcpu_initialized(vcpu)) > > + return -ENOEXEC; > > + > > + if (get_user(what, (const int __user *)argp)) > > + return -EFAULT; > > + > > + return kvm_arm_vcpu_finalize(vcpu, what); > > Almost all the cases use the 'r = ...; break;' type of pattern, leaving > it to the 'return r' at the end of the function. I guess that's in case > at some point more stuff is added after the switch. The only cases that > don't do that are the most recent ones KVM_GET/SET_VCPU_EVENTS, which > should probably be changed to fit the pattern too, rather than this > new ioctl following there pattern. I have no strong opinion on this: it's basically a question of style. I followed KVM_GET/SET_VCPU_EVENTS, but you're right, the r = ...; break; style is used for the others. If there's an intention of putting stuff at the end of the function, it will make a difference. But this seems unlikely to happen: this function is really just a dispatcher. I'm happy to change it (and the others) if there are strong views. Cheers ---Dave
diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h index a49ee01..e80cfc1 100644 --- a/arch/arm/include/asm/kvm_host.h +++ b/arch/arm/include/asm/kvm_host.h @@ -19,6 +19,7 @@ #ifndef __ARM_KVM_HOST_H__ #define __ARM_KVM_HOST_H__ +#include <linux/errno.h> #include <linux/types.h> #include <linux/kvm_types.h> #include <asm/cputype.h> @@ -411,4 +412,7 @@ static inline int kvm_arm_setup_stage2(struct kvm *kvm, unsigned long type) return 0; } +#define kvm_arm_vcpu_finalize(vcpu, what) (-EINVAL) +#define kvm_arm_vcpu_is_finalized(vcpu) true + #endif /* __ARM_KVM_HOST_H__ */ diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index 3e89509..98658f7 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -23,6 +23,7 @@ #define __ARM64_KVM_HOST_H__ #include <linux/bitmap.h> +#include <linux/errno.h> #include <linux/types.h> #include <linux/jump_label.h> #include <linux/kvm_types.h> @@ -625,4 +626,7 @@ void kvm_arch_free_vm(struct kvm *kvm); int kvm_arm_setup_stage2(struct kvm *kvm, unsigned long type); +#define kvm_arm_vcpu_finalize(vcpu, what) (-EINVAL) +#define kvm_arm_vcpu_is_finalized(vcpu) true + #endif /* __ARM64_KVM_HOST_H__ */ diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index dc77a5a..c3b8e7a 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -1441,6 +1441,9 @@ struct kvm_enc_region { /* Available with KVM_CAP_HYPERV_CPUID */ #define KVM_GET_SUPPORTED_HV_CPUID _IOWR(KVMIO, 0xc1, struct kvm_cpuid2) +/* Available with KVM_CAP_ARM_SVE */ +#define KVM_ARM_VCPU_FINALIZE _IOW(KVMIO, 0xc2, int) + /* Secure Encrypted Virtualization command */ enum sev_cmd_id { /* Guest initialization commands */ diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c index c69e137..9edbf0f 100644 --- a/virt/kvm/arm/arm.c +++ b/virt/kvm/arm/arm.c @@ -545,6 +545,9 @@ static int kvm_vcpu_first_run_init(struct kvm_vcpu *vcpu) if (likely(vcpu->arch.has_run_once)) return 0; + if (!kvm_arm_vcpu_is_finalized(vcpu)) + return -EPERM; + vcpu->arch.has_run_once = true; if (likely(irqchip_in_kernel(kvm))) { @@ -1116,6 +1119,10 @@ long kvm_arch_vcpu_ioctl(struct file *filp, if (unlikely(!kvm_vcpu_initialized(vcpu))) break; + r = -EPERM; + if (!kvm_arm_vcpu_is_finalized(vcpu)) + break; + r = -EFAULT; if (copy_from_user(®_list, user_list, sizeof(reg_list))) break; @@ -1169,6 +1176,17 @@ long kvm_arch_vcpu_ioctl(struct file *filp, return kvm_arm_vcpu_set_events(vcpu, &events); } + case KVM_ARM_VCPU_FINALIZE: { + int what; + + if (!kvm_vcpu_initialized(vcpu)) + return -ENOEXEC; + + if (get_user(what, (const int __user *)argp)) + return -EFAULT; + + return kvm_arm_vcpu_finalize(vcpu, what); + } default: r = -EINVAL; }