Message ID | 20210610174604.2554090-1-alpergun@google.com (mailing list archive) |
---|---|
State | New, archived |
Headers | show |
Series | KVM: SVM: Call SEV Guest Decommission if ASID binding fails | expand |
On Thu, Jun 10, 2021 at 10:46 AM Alper Gun <alpergun@google.com> wrote: > > 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> > --- > arch/x86/kvm/svm/sev.c | 20 +++++++++++++++----- > 1 file changed, 15 insertions(+), 5 deletions(-) > > diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c > index e0ce5da97fc2..8d36f0c73071 100644 > --- a/arch/x86/kvm/svm/sev.c > +++ b/arch/x86/kvm/svm/sev.c > @@ -199,9 +199,19 @@ static void sev_asid_free(struct kvm_sev_info *sev) > sev->misc_cg = NULL; > } > > -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.handle = handle; > + sev_guest_decommission(&decommission, NULL); > +} > + > +static void sev_unbind_asid(struct kvm *kvm, unsigned int handle) > +{ > struct sev_data_deactivate deactivate; > > if (!handle) > @@ -214,9 +224,7 @@ static void sev_unbind_asid(struct kvm *kvm, unsigned int handle) > sev_guest_deactivate(&deactivate, NULL); > up_read(&sev_deactivate_lock); > > - /* decommission handle */ > - decommission.handle = handle; > - sev_guest_decommission(&decommission, NULL); > + sev_decommission(handle); > } > > static int sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp) > @@ -341,8 +349,10 @@ 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; > -- > 2.32.0.272.g935e593368-goog > Reviewed-by: Marc Orr <marcorr@google.com>
On 10/06/21 19:46, Alper Gun wrote: > 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> > --- > arch/x86/kvm/svm/sev.c | 20 +++++++++++++++----- > 1 file changed, 15 insertions(+), 5 deletions(-) > > diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c > index e0ce5da97fc2..8d36f0c73071 100644 > --- a/arch/x86/kvm/svm/sev.c > +++ b/arch/x86/kvm/svm/sev.c > @@ -199,9 +199,19 @@ static void sev_asid_free(struct kvm_sev_info *sev) > sev->misc_cg = NULL; > } > > -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.handle = handle; > + sev_guest_decommission(&decommission, NULL); > +} > + > +static void sev_unbind_asid(struct kvm *kvm, unsigned int handle) > +{ > struct sev_data_deactivate deactivate; > > if (!handle) > @@ -214,9 +224,7 @@ static void sev_unbind_asid(struct kvm *kvm, unsigned int handle) > sev_guest_deactivate(&deactivate, NULL); > up_read(&sev_deactivate_lock); > > - /* decommission handle */ > - decommission.handle = handle; > - sev_guest_decommission(&decommission, NULL); > + sev_decommission(handle); > } > > static int sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp) > @@ -341,8 +349,10 @@ 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; > Queued, thanks. Paolo
diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index e0ce5da97fc2..8d36f0c73071 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -199,9 +199,19 @@ static void sev_asid_free(struct kvm_sev_info *sev) sev->misc_cg = NULL; } -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.handle = handle; + sev_guest_decommission(&decommission, NULL); +} + +static void sev_unbind_asid(struct kvm *kvm, unsigned int handle) +{ struct sev_data_deactivate deactivate; if (!handle) @@ -214,9 +224,7 @@ static void sev_unbind_asid(struct kvm *kvm, unsigned int handle) sev_guest_deactivate(&deactivate, NULL); up_read(&sev_deactivate_lock); - /* decommission handle */ - decommission.handle = handle; - sev_guest_decommission(&decommission, NULL); + sev_decommission(handle); } static int sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp) @@ -341,8 +349,10 @@ 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;
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> --- arch/x86/kvm/svm/sev.c | 20 +++++++++++++++----- 1 file changed, 15 insertions(+), 5 deletions(-)