| Message ID | 20210624234855.2428305-1-alpergun@google.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [5.10,v2] KVM: SVM: Call SEV Guest Decommission if ASID binding fails | expand |
On 25/06/21 01:48, Alper Gun wrote: > commit 934002cd660b035b926438244b4294e647507e13 upstream. > > Send SEV_CMD_DECOMMISSION command to PSP firmware if ASID binding > fails. If a failure happens after a successful LAUNCH_START command, > a decommission command should be executed. Otherwise, guest context > will be unfreed inside the AMD SP. After the firmware will not have > memory to allocate more SEV guest context, LAUNCH_START command will > begin to fail with SEV_RET_RESOURCE_LIMIT error. > > The existing code calls decommission inside sev_unbind_asid, but it is > not called if a failure happens before guest activation succeeds. If > sev_bind_asid fails, decommission is never called. PSP firmware has a > limit for the number of guests. If sev_asid_binding fails many times, > PSP firmware will not have resources to create another guest context. > > Cc: stable@vger.kernel.org > Fixes: 59414c989220 ("KVM: SVM: Add support for KVM_SEV_LAUNCH_START command") > Reported-by: Peter Gonda <pgonda@google.com> > Signed-off-by: Alper Gun <alpergun@google.com> > Reviewed-by: Marc Orr <marcorr@google.com> > Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> > --- > arch/x86/kvm/svm/sev.c | 32 +++++++++++++++++++++----------- > 1 file changed, 21 insertions(+), 11 deletions(-) > > diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c > index 16b10b9436dc..01547bdbfb06 100644 > --- a/arch/x86/kvm/svm/sev.c > +++ b/arch/x86/kvm/svm/sev.c > @@ -130,9 +130,25 @@ static void sev_asid_free(int asid) > mutex_unlock(&sev_bitmap_lock); > } > > -static void sev_unbind_asid(struct kvm *kvm, unsigned int handle) > +static void sev_decommission(unsigned int handle) > { > struct sev_data_decommission *decommission; > + > + if (!handle) > + return; > + > + decommission = kzalloc(sizeof(*decommission), GFP_KERNEL); > + if (!decommission) > + return; > + > + decommission->handle = handle; > + sev_guest_decommission(decommission, NULL); > + > + kfree(decommission); > +} > + > +static void sev_unbind_asid(struct kvm *kvm, unsigned int handle) > +{ > struct sev_data_deactivate *data; > > if (!handle) > @@ -152,15 +168,7 @@ static void sev_unbind_asid(struct kvm *kvm, unsigned int handle) > > kfree(data); > > - decommission = kzalloc(sizeof(*decommission), GFP_KERNEL); > - if (!decommission) > - return; > - > - /* decommission handle */ > - decommission->handle = handle; > - sev_guest_decommission(decommission, NULL); > - > - kfree(decommission); > + sev_decommission(handle); > } > > static int sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp) > @@ -288,8 +296,10 @@ static int sev_launch_start(struct kvm *kvm, struct kvm_sev_cmd *argp) > > /* Bind ASID to this guest */ > ret = sev_bind_asid(kvm, start->handle, error); > - if (ret) > + if (ret) { > + sev_decommission(start->handle); > goto e_free_session; > + } > > /* return handle to userspace */ > params.handle = start->handle; > Acked-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index 16b10b9436dc..01547bdbfb06 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -130,9 +130,25 @@ static void sev_asid_free(int asid) mutex_unlock(&sev_bitmap_lock); } -static void sev_unbind_asid(struct kvm *kvm, unsigned int handle) +static void sev_decommission(unsigned int handle) { struct sev_data_decommission *decommission; + + if (!handle) + return; + + decommission = kzalloc(sizeof(*decommission), GFP_KERNEL); + if (!decommission) + return; + + decommission->handle = handle; + sev_guest_decommission(decommission, NULL); + + kfree(decommission); +} + +static void sev_unbind_asid(struct kvm *kvm, unsigned int handle) +{ struct sev_data_deactivate *data; if (!handle) @@ -152,15 +168,7 @@ static void sev_unbind_asid(struct kvm *kvm, unsigned int handle) kfree(data); - decommission = kzalloc(sizeof(*decommission), GFP_KERNEL); - if (!decommission) - return; - - /* decommission handle */ - decommission->handle = handle; - sev_guest_decommission(decommission, NULL); - - kfree(decommission); + sev_decommission(handle); } static int sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp) @@ -288,8 +296,10 @@ static int sev_launch_start(struct kvm *kvm, struct kvm_sev_cmd *argp) /* Bind ASID to this guest */ ret = sev_bind_asid(kvm, start->handle, error); - if (ret) + if (ret) { + sev_decommission(start->handle); goto e_free_session; + } /* return handle to userspace */ params.handle = start->handle;
commit 934002cd660b035b926438244b4294e647507e13 upstream. Send SEV_CMD_DECOMMISSION command to PSP firmware if ASID binding fails. If a failure happens after a successful LAUNCH_START command, a decommission command should be executed. Otherwise, guest context will be unfreed inside the AMD SP. After the firmware will not have memory to allocate more SEV guest context, LAUNCH_START command will begin to fail with SEV_RET_RESOURCE_LIMIT error. The existing code calls decommission inside sev_unbind_asid, but it is not called if a failure happens before guest activation succeeds. If sev_bind_asid fails, decommission is never called. PSP firmware has a limit for the number of guests. If sev_asid_binding fails many times, PSP firmware will not have resources to create another guest context. Cc: stable@vger.kernel.org Fixes: 59414c989220 ("KVM: SVM: Add support for KVM_SEV_LAUNCH_START command") Reported-by: Peter Gonda <pgonda@google.com> Signed-off-by: Alper Gun <alpergun@google.com> Reviewed-by: Marc Orr <marcorr@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> --- arch/x86/kvm/svm/sev.c | 32 +++++++++++++++++++++----------- 1 file changed, 21 insertions(+), 11 deletions(-)