KVM: SVM: move sev_decommission to psp driver

ccp/sev-dev.c is part of the software layer in psp that allows KVM to
manage SEV/ES/SNP enabled VMs. Among the APIs exposed in sev-dev, many of
them requires caller (KVM) to understand psp specific data structures. This
often ends up with the fact that KVM has to create its own 'wrapper' API to
make it easy to use. The following is the pattern:

kvm_func(unsigned int handle)
{
	psp_data_structure data;

	data.handle = handle;
	psp_func(&data, NULL);
}

psp_func(psp_data_structure *data, int *error)
{
	sev_do_cmd(data, error);
}

struct psp_data_structure {
	u32 handle;
};

sev_decommission is one example following the above pattern. Since KVM is
the only user for this API and 'handle' is the only data that is meaningful
to KVM, simplify the interface by putting the code from kvm function
sev_decommission into the psp function sev_guest_decomssion.

Cc: Alper Gun <alpergun@google.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Cc: David Rienjes <rientjes@google.com>
Cc: Marc Orr <marcorr@google.com>
Cc: John Allen <john.allen@amd.com>
Cc: Peter Gonda <pgonda@google.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Vipin Sharma <vipinsh@google.com>

Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Mingwei Zhang <mizhang@google.com>

arch/x86/kvm/svm/sev.c

@@ -198,17 +198,6 @@ static void sev_asid_free(struct kvm_sev_info *sev)
 	sev->misc_cg = NULL;
 }
 
-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;
@@ -223,7 +212,7 @@ static void sev_unbind_asid(struct kvm *kvm, unsigned int handle)
 	sev_guest_deactivate(&deactivate, NULL);
 	up_read(&sev_deactivate_lock);
 
-	sev_decommission(handle);
+	sev_guest_decommission(handle, NULL);
 }
 
 static int sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp)
@@ -349,7 +338,7 @@ 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) {
-		sev_decommission(start.handle);
+		sev_guest_decommission(start.handle, NULL);
 		goto e_free_session;
 	}
 

drivers/crypto/ccp/sev-dev.c

@@ -903,8 +903,14 @@ int sev_guest_activate(struct sev_data_activate *data, int *error)
 }
 EXPORT_SYMBOL_GPL(sev_guest_activate);
 
-int sev_guest_decommission(struct sev_data_decommission *data, int *error)
+int sev_guest_decommission(unsigned int handle, int *error)
 {
+	struct sev_data_decommission decommission;
+
+	if (!handle)
+		return -EINVAL;
+
+	decommission.handle = handle;
 	return sev_do_cmd(SEV_CMD_DECOMMISSION, data, error);
 }
 EXPORT_SYMBOL_GPL(sev_guest_decommission);

include/linux/psp-sev.h

@@ -612,17 +612,18 @@ int sev_guest_df_flush(int *error);
 /**
  * sev_guest_decommission - perform SEV DECOMMISSION command
  *
- * @decommission: sev_data_decommission structure to be processed
+ * @handle: sev_data_decommission structure to be processed
  * @sev_ret: sev command return code
  *
  * Returns:
  * 0 if the sev successfully processed the command
+ * -%EINVAL    if handle is NULL
  * -%ENODEV    if the sev device is not available
  * -%ENOTSUPP  if the sev does not support SEV
  * -%ETIMEDOUT if the sev command timed out
  * -%EIO       if the sev returned a non-zero return code
  */
-int sev_guest_decommission(struct sev_data_decommission *data, int *error);
+int sev_guest_decommission(unsigned int handle, int *error);
 
 void *psp_copy_user_blob(u64 uaddr, u32 len);
 
@@ -637,7 +638,7 @@ static inline int
 sev_guest_deactivate(struct sev_data_deactivate *data, int *error) { return -ENODEV; }
 
 static inline int
-sev_guest_decommission(struct sev_data_decommission *data, int *error) { return -ENODEV; }
+sev_guest_decommission(unsigned int handle, int *error) { return -ENODEV; }
 
 static inline int
 sev_guest_activate(struct sev_data_activate *data, int *error) { return -ENODEV; }