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KVM: SVM: Call SEV Guest Decommission if ASID binding fails

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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>
Message-Id: <20210610174604.2554090-1-alpergun@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Alper Gun 2021-06-10 17:46:04 +00:00 committed by Sasha Levin
parent 377a796e7a
commit 7570a8b5dd
1 changed files with 21 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

32
arch/x86/kvm/svm/sev.c
View File

@ -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;