[6.6]Hygon: Support reuse ASID feature for Hygon CSV

arch/x86/kvm/Kconfig

@@ -154,4 +154,14 @@ config KVM_PROVE_MMU
 config KVM_EXTERNAL_WRITE_TRACKING
 	bool
 
+config KVM_SUPPORTS_CSV_REUSE_ASID
+	def_bool y
+	bool "Reuse the same ASID for different HYGON CSV guests"
+	depends on KVM_AMD_SEV && CPU_SUP_HYGON && HYGON_CSV
+	depends on !CGROUP_MISC
+	help
+	  Provide support for reuse the same ASID for difference HYGON
+	  CSV guests, this allow the user to create more CSV guests on
+	  HYGON CPUs with limited ASIDs.
+
 endif # VIRTUALIZATION

arch/x86/kvm/svm/csv.c

@@ -1068,6 +1068,33 @@ static int csv_control_post_system_reset(struct kvm *kvm)
 	return 0;
 }
 
+#ifdef CONFIG_KVM_SUPPORTS_CSV_REUSE_ASID
+
+struct csv_asid_userid *csv_asid_userid_array;
+
+int csv_alloc_asid_userid_array(unsigned int nr_asids)
+{
+	int ret = 0;
+
+	csv_asid_userid_array = kcalloc(nr_asids, sizeof(struct csv_asid_userid),
+					GFP_KERNEL_ACCOUNT);
+	if (!csv_asid_userid_array)
+		ret = -ENOMEM;
+
+	if (ret)
+		pr_warn("Fail to allocate array, reuse ASID is unavailable\n");
+
+	return ret;
+}
+
+void csv_free_asid_userid_array(void)
+{
+	kfree(csv_asid_userid_array);
+	csv_asid_userid_array = NULL;
+}
+
+#endif	/* CONFIG_KVM_SUPPORTS_CSV_REUSE_ASID */
+
 void csv_exit(void)
 {
 }

arch/x86/kvm/svm/csv.h

@@ -32,6 +32,28 @@ struct csv_ringbuf_infos {
 	int num;
 };
 
+#ifdef CONFIG_KVM_SUPPORTS_CSV_REUSE_ASID
+
+#define ASID_USERID_LENGTH 20
+
+struct csv_asid_userid {
+	int refcnt; // reference count of the ASID
+	u32 userid_len;
+	char userid[ASID_USERID_LENGTH];
+};
+
+extern struct csv_asid_userid *csv_asid_userid_array;
+
+int csv_alloc_asid_userid_array(unsigned int nr_asids);
+void csv_free_asid_userid_array(void);
+
+#else
+
+static inline int csv_alloc_asid_userid_array(unsigned int nr_asids) { return -ENOMEM; }
+static inline void csv_free_asid_userid_array(void) { }
+
+#endif	/* CONFIG_KVM_SUPPORTS_CSV_REUSE_ASID */
+
 #ifdef CONFIG_HYGON_CSV
 
 /*

arch/x86/kvm/svm/sev.c

@@ -145,7 +145,11 @@ static void sev_misc_cg_uncharge(struct kvm_sev_info *sev)
 	misc_cg_uncharge(type, sev->misc_cg, 1);
 }
 
+#ifdef CONFIG_KVM_SUPPORTS_CSV_REUSE_ASID
+static int sev_asid_new(struct kvm_sev_info *sev, const char *userid, u32 userid_len)
+#else
 static int sev_asid_new(struct kvm_sev_info *sev)
+#endif
 {
 	/*
 	 * SEV-enabled guests must use asid from min_sev_asid to max_sev_asid.
@@ -173,6 +177,34 @@ static int sev_asid_new(struct kvm_sev_info *sev)
 
 	mutex_lock(&sev_bitmap_lock);
 
+#ifdef CONFIG_KVM_SUPPORTS_CSV_REUSE_ASID
+	/* For Hygon CPU, check whether the userid exists */
+	if (is_x86_vendor_hygon() && userid && userid_len &&
+	    !WARN_ON_ONCE(!csv_asid_userid_array)) {
+		int i = !min_sev_asid ? 1 : min_sev_asid;
+
+		for (; i <= max_sev_asid; i++) {
+			/* skip ASIDs without correspond userid */
+			if (!csv_asid_userid_array[i].userid_len)
+				continue;
+
+			/* skip if length of userid is different */
+			if (csv_asid_userid_array[i].userid_len != userid_len)
+				continue;
+
+			if (!memcmp(csv_asid_userid_array[i].userid,
+				    userid, userid_len)) {
+				pr_debug("Found reusable asid %d\n", i);
+				/* Increase reference count if userid exists */
+				csv_asid_userid_array[i].refcnt++;
+
+				mutex_unlock(&sev_bitmap_lock);
+				return i;
+			}
+		}
+	}
+#endif
+
 again:
 	asid = find_next_zero_bit(sev_asid_bitmap, max_asid + 1, min_asid);
 	if (asid > max_asid) {
@@ -187,6 +219,16 @@ static int sev_asid_new(struct kvm_sev_info *sev)
 
 	__set_bit(asid, sev_asid_bitmap);
 
+#ifdef CONFIG_KVM_SUPPORTS_CSV_REUSE_ASID
+	/* For Hygon CPU, initialize the new userid */
+	if (is_x86_vendor_hygon() && userid && userid_len &&
+	    !WARN_ON_ONCE(!csv_asid_userid_array)) {
+		memcpy(csv_asid_userid_array[asid].userid, userid, userid_len);
+		csv_asid_userid_array[asid].userid_len = userid_len;
+		csv_asid_userid_array[asid].refcnt = 1;
+	}
+#endif
+
 	mutex_unlock(&sev_bitmap_lock);
 
 	return asid;
@@ -211,7 +253,25 @@ static void sev_asid_free(struct kvm_sev_info *sev)
 
 	mutex_lock(&sev_bitmap_lock);
 
+#ifdef CONFIG_KVM_SUPPORTS_CSV_REUSE_ASID
+	/* For Hygon CPU, decrease the reference count if userid exist */
+	if (!is_x86_vendor_hygon() || !csv_asid_userid_array ||
+	    !csv_asid_userid_array[sev->asid].userid_len) {
+		__set_bit(sev->asid, sev_reclaim_asid_bitmap);
+	} else {
+		/* If reach here, reference count should large than 0. */
+		WARN_ON(csv_asid_userid_array[sev->asid].refcnt <= 0);
+
+		if (--csv_asid_userid_array[sev->asid].refcnt == 0) {
+			__set_bit(sev->asid, sev_reclaim_asid_bitmap);
+
+			memset(&csv_asid_userid_array[sev->asid], 0,
+			       sizeof(struct csv_asid_userid));
+		}
+	}
+#else
 	__set_bit(sev->asid, sev_reclaim_asid_bitmap);
+#endif
 
 	for_each_possible_cpu(cpu) {
 		sd = per_cpu_ptr(&svm_data, cpu);
@@ -267,7 +327,46 @@ static int sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp)
 
 	sev->active = true;
 	sev->es_active = argp->id == KVM_SEV_ES_INIT;
+
+#ifdef CONFIG_KVM_SUPPORTS_CSV_REUSE_ASID
+	/* Try reuse ASID iff userid array is available for HYGON CSV guests */
+	if (is_x86_vendor_hygon() && csv_asid_userid_array) {
+		struct kvm_csv_init params;
+		void *csv_blob = NULL;
+
+		memset(&params, 0, sizeof(params));
+
+		if (argp->data &&
+		    copy_from_user(&params,
+				(void __user *)(uintptr_t)argp->data, sizeof(params)))
+			return -EFAULT;
+
+		if (params.userid_addr) {
+			if (params.len >= ASID_USERID_LENGTH) {
+				pr_err("Invalid length of userid %d > %d\n",
+				       params.len, ASID_USERID_LENGTH);
+				return -EINVAL;
+			}
+
+			csv_blob = psp_copy_user_blob(params.userid_addr, params.len);
+			if (IS_ERR(csv_blob)) {
+				pr_err("Copy userid failed, %llx (%u)\n",
+				       params.userid_addr, params.len);
+				return PTR_ERR(csv_blob);
+			}
+		}
+
+		asid = sev_asid_new(sev, (const char *)csv_blob, params.len);
+
+		/* The buffer @csv_blob is no longer used, free it. */
+		kfree(csv_blob);
+	} else {
+		asid = sev_asid_new(sev, NULL, 0);
+	}
+#else
 	asid = sev_asid_new(sev);
+#endif
+
 	if (asid < 0)
 		goto e_no_asid;
 	sev->asid = asid;
@@ -2345,13 +2444,19 @@ void __init sev_hardware_setup(void)
 		 */
 		sev_install_hooks();
 
-		/*
-		 * Allocate a memory pool to speed up live migration of
-		 * the CSV/CSV2 guests. If the allocation fails, no
-		 * acceleration is performed at live migration.
-		 */
-		if (sev_enabled)
+		if (sev_enabled) {
+			/*
+			 * Allocate a memory pool to speed up live migration of
+			 * the CSV/CSV2 guests. If the allocation fails, no
+			 * acceleration is performed at live migration.
+			 */
 			csv_alloc_trans_mempool();
+			/*
+			 * Allocate a buffer to support reuse ASID, reuse ASID
+			 * will not work if the allocation fails.
+			 */
+			csv_alloc_asid_userid_array(nr_asids);
+		}
 	}
 #endif
 
@@ -2363,9 +2468,11 @@ void sev_hardware_unsetup(void)
 	if (!sev_enabled)
 		return;
 
-	/* Free the memory pool that allocated in sev_hardware_setup(). */
-	if (is_x86_vendor_hygon())
+	/* Free the memory that allocated in sev_hardware_setup(). */
+	if (is_x86_vendor_hygon()) {
 		csv_free_trans_mempool();
+		csv_free_asid_userid_array();
+	}
 
 	/* No need to take sev_bitmap_lock, all VMs have been destroyed. */
 	sev_flush_asids(1, max_sev_asid);
@@ -2721,6 +2828,13 @@ void pre_sev_run(struct vcpu_svm *svm, int cpu)
 	/* Assign the asid allocated with this SEV guest */
 	svm->asid = asid;
 
+#ifdef CONFIG_KVM_SUPPORTS_CSV_REUSE_ASID
+	/* If ASID is shared with other guests, then flush TLB before VMRUN */
+	if (is_x86_vendor_hygon() && csv_asid_userid_array &&
+	    csv_asid_userid_array[asid].userid_len)
+		svm->vmcb->control.tlb_ctl = TLB_CONTROL_FLUSH_ASID;
+#endif
+
 	/*
 	 * Flush guest TLB:
 	 *

include/uapi/linux/kvm.h

@@ -2301,6 +2301,11 @@ struct kvm_csv_receive_update_vmsa {
 	__u32 trans_len;
 };
 
+struct kvm_csv_init {
+	__u64 userid_addr;
+	__u32 len;
+};
+
 /* ioctls for control vm during system reset, currently only for CSV */
 #define KVM_CONTROL_PRE_SYSTEM_RESET	 _IO(KVMIO, 0xe8)
 #define KVM_CONTROL_POST_SYSTEM_RESET	 _IO(KVMIO, 0xe9)