sbi: sbi_domain_context: Add spinlock for updating domain assigned_harts

Add spinlock protection to avoid race condition on assigned_harts
during domain context switching. Also, rename/add variables for
accessing the corresponding domain of target/current context.

Signed-off-by: Alvin Chang <alvinga@andestech.com>
Reviewed-by: Yu Chien Peter Lin <peterlin@andestech.com>
Reviewed-by: Anup Patel <anup@brainfault.org>

4 files changed, 55 insertions, 18 deletions

diff --git a/include/sbi/sbi_domain.h b/include/sbi/sbi_domain.h
index 4706cfc..a6e99c6 100644
--- a/include/sbi/sbi_domain.h
+++ b/include/sbi/sbi_domain.h
@@ -10,6 +10,7 @@
 #ifndef __SBI_DOMAIN_H__
 #define __SBI_DOMAIN_H__
 
+#include <sbi/riscv_locks.h>
 #include <sbi/sbi_types.h>
 #include <sbi/sbi_hartmask.h>
 #include <sbi/sbi_domain_context.h>
@@ -173,6 +174,8 @@ struct sbi_domain {
 	 * in the coldboot path
 	 */
 	struct sbi_hartmask assigned_harts;
+	/** Spinlock for accessing assigned_harts */
+	spinlock_t assigned_harts_lock;
 	/** Name of this domain */
 	char name[64];
 	/** Possible HARTs in this domain */
diff --git a/lib/sbi/sbi_domain.c b/lib/sbi/sbi_domain.c
index 50749f1..374ac36 100644
--- a/lib/sbi/sbi_domain.c
+++ b/lib/sbi/sbi_domain.c
@@ -64,20 +64,34 @@ void sbi_update_hartindex_to_domain(u32 hartindex, struct sbi_domain *dom)
 
 bool sbi_domain_is_assigned_hart(const struct sbi_domain *dom, u32 hartid)
 {
-	if (dom)
-		return sbi_hartmask_test_hartid(hartid, &dom->assigned_harts);
+	bool ret;
+	struct sbi_domain *tdom = (struct sbi_domain *)dom;
 
-	return false;
+	if (!dom)
+		return false;
+
+	spin_lock(&tdom->assigned_harts_lock);
+	ret = sbi_hartmask_test_hartid(hartid, &tdom->assigned_harts);
+	spin_unlock(&tdom->assigned_harts_lock);
+
+	return ret;
 }
 
 ulong sbi_domain_get_assigned_hartmask(const struct sbi_domain *dom,
 				       ulong hbase)
 {
 	ulong ret = 0;
+	struct sbi_domain *tdom = (struct sbi_domain *)dom;
+
+	if (!dom)
+		return 0;
+
+	spin_lock(&tdom->assigned_harts_lock);
 	for (int i = 0; i < 8 * sizeof(ret); i++) {
-		if (sbi_domain_is_assigned_hart(dom, hbase + i))
+		if (sbi_hartmask_test_hartid(hbase + i, &tdom->assigned_harts))
 			ret |= 1UL << i;
 	}
+	spin_unlock(&tdom->assigned_harts_lock);
 
 	return ret;
 }
@@ -555,6 +569,9 @@ int sbi_domain_register(struct sbi_domain *dom,
 	dom->index = domain_count++;
 	domidx_to_domain_table[dom->index] = dom;
 
+	/* Initialize spinlock for dom->assigned_harts */
+	SPIN_LOCK_INIT(dom->assigned_harts_lock);
+
 	/* Clear assigned HARTs of domain */
 	sbi_hartmask_clear_all(&dom->assigned_harts);
 
@@ -701,8 +718,14 @@ int sbi_domain_finalize(struct sbi_scratch *scratch, u32 cold_hartid)
 			continue;
 
 		/* Ignore if boot HART assigned different domain */
-		if (sbi_hartindex_to_domain(dhart) != dom ||
-		    !sbi_hartmask_test_hartindex(dhart, &dom->assigned_harts))
+		if (sbi_hartindex_to_domain(dhart) != dom)
+			continue;
+
+		/* Ignore if boot HART is not part of the assigned HARTs */
+		spin_lock(&dom->assigned_harts_lock);
+		rc = sbi_hartmask_test_hartindex(dhart, &dom->assigned_harts);
+		spin_unlock(&dom->assigned_harts_lock);
+		if (!rc)
 			continue;
 
 		/* Startup boot HART of domain */
diff --git a/lib/sbi/sbi_domain_context.c b/lib/sbi/sbi_domain_context.c
index 8daf629..7528591 100755
--- a/lib/sbi/sbi_domain_context.c
+++ b/lib/sbi/sbi_domain_context.c
@@ -26,18 +26,23 @@
 static void switch_to_next_domain_context(struct sbi_context *ctx,
 					  struct sbi_context *dom_ctx)
 {
-	u32 hartindex;
+	u32 hartindex = sbi_hartid_to_hartindex(current_hartid());
 	struct sbi_trap_regs *trap_regs;
-	struct sbi_domain *dom = dom_ctx->dom;
+	struct sbi_domain *current_dom = ctx->dom;
+	struct sbi_domain *target_dom = dom_ctx->dom;
 	struct sbi_scratch *scratch = sbi_scratch_thishart_ptr();
 	unsigned int pmp_count = sbi_hart_pmp_count(scratch);
 
 	/* Assign current hart to target domain */
-	hartindex = sbi_hartid_to_hartindex(current_hartid());
-	sbi_hartmask_clear_hartindex(
-		hartindex, &sbi_domain_thishart_ptr()->assigned_harts);
-	sbi_update_hartindex_to_domain(hartindex, dom);
-	sbi_hartmask_set_hartindex(hartindex, &dom->assigned_harts);
+	spin_lock(&current_dom->assigned_harts_lock);
+	sbi_hartmask_clear_hartindex(hartindex, &current_dom->assigned_harts);
+	spin_unlock(&current_dom->assigned_harts_lock);
+
+	sbi_update_hartindex_to_domain(hartindex, target_dom);
+
+	spin_lock(&target_dom->assigned_harts_lock);
+	sbi_hartmask_set_hartindex(hartindex, &target_dom->assigned_harts);
+	spin_unlock(&target_dom->assigned_harts_lock);
 
 	/* Reconfigure PMP settings for the new domain */
 	for (int i = 0; i < pmp_count; i++) {
@@ -72,9 +77,11 @@ static void switch_to_next_domain_context(struct sbi_context *ctx,
 	/* If target domain context is not initialized or runnable */
 	if (!dom_ctx->initialized) {
 		/* Startup boot HART of target domain */
-		if (current_hartid() == dom->boot_hartid)
-			sbi_hart_switch_mode(dom->boot_hartid, dom->next_arg1,
-					     dom->next_addr, dom->next_mode,
+		if (current_hartid() == target_dom->boot_hartid)
+			sbi_hart_switch_mode(target_dom->boot_hartid,
+					     target_dom->next_arg1,
+					     target_dom->next_addr,
+					     target_dom->next_mode,
 					     false);
 		else
 			sbi_hsm_hart_stop(scratch, true);
diff --git a/lib/sbi/sbi_system.c b/lib/sbi/sbi_system.c
index e930272..c068b72 100644
--- a/lib/sbi/sbi_system.c
+++ b/lib/sbi/sbi_system.c
@@ -148,7 +148,7 @@ bool sbi_system_suspend_supported(u32 sleep_type)
 
 int sbi_system_suspend(u32 sleep_type, ulong resume_addr, ulong opaque)
 {
-	const struct sbi_domain *dom = sbi_domain_thishart_ptr();
+	struct sbi_domain *dom = sbi_domain_thishart_ptr();
 	struct sbi_scratch *scratch = sbi_scratch_thishart_ptr();
 	void (*jump_warmboot)(void) = (void (*)(void))scratch->warmboot_addr;
 	unsigned int hartid = current_hartid();
@@ -171,13 +171,17 @@ int sbi_system_suspend(u32 sleep_type, ulong resume_addr, ulong opaque)
 	if (prev_mode != PRV_S && prev_mode != PRV_U)
 		return SBI_EFAIL;
 
+	spin_lock(&dom->assigned_harts_lock);
 	sbi_hartmask_for_each_hartindex(j, &dom->assigned_harts) {
 		i = sbi_hartindex_to_hartid(j);
 		if (i == hartid)
 			continue;
-		if (__sbi_hsm_hart_get_state(i) != SBI_HSM_STATE_STOPPED)
+		if (__sbi_hsm_hart_get_state(i) != SBI_HSM_STATE_STOPPED) {
+			spin_unlock(&dom->assigned_harts_lock);
 			return SBI_ERR_DENIED;
+		}
 	}
+	spin_unlock(&dom->assigned_harts_lock);
 
 	if (!sbi_domain_check_addr(dom, resume_addr, prev_mode,
 				   SBI_DOMAIN_EXECUTE))