From aee9f3c666adbc56b4529a225e78f149769fbf47 Mon Sep 17 00:00:00 2001
From: Zide Chen <zide.chen@intel.com>
Date: Wed, 17 Apr 2019 11:41:21 -0700
Subject: [PATCH] hv: reset per cpu sbuf pointers during vcpu reset

When shutting down SOS VM, the shared sbuf is released from guest OS, but
the per cpu sbuf pointers in hypervisor keep inact. This creates a problem
that after SOS is re-launched, hypervisor could write to the shared
buffer that no longer exists.

This patch implements sbuf_reset() and call it from reset_vcpu() to
reset sbuf pointers.

Tracked-On: #2700
Signed-off-by: Zide Chen <zide.chen@intel.com>
Acked-by: Anthony Xu <anthony.xu@intel.com>
---
 hypervisor/arch/x86/guest/vcpu.c |  2 ++
 hypervisor/debug/sbuf.c          | 11 +++++++++++
 hypervisor/include/debug/sbuf.h  |  1 +
 hypervisor/release/sbuf.c        | 10 ++++++++++
 4 files changed, 24 insertions(+)
 create mode 100644 hypervisor/release/sbuf.c

diff --git a/hypervisor/arch/x86/guest/vcpu.c b/hypervisor/arch/x86/guest/vcpu.c
index 81bcc1a75..202352fb4 100644
--- a/hypervisor/arch/x86/guest/vcpu.c
+++ b/hypervisor/arch/x86/guest/vcpu.c
@@ -582,6 +582,8 @@ void reset_vcpu(struct acrn_vcpu *vcpu)
 	vlapic = vcpu_vlapic(vcpu);
 	vlapic_reset(vlapic);
 
+	sbuf_reset(vcpu->pcpu_id);
+
 	reset_vcpu_regs(vcpu);
 }
 
diff --git a/hypervisor/debug/sbuf.c b/hypervisor/debug/sbuf.c
index bc7353f48..a53a60b84 100644
--- a/hypervisor/debug/sbuf.c
+++ b/hypervisor/debug/sbuf.c
@@ -121,3 +121,14 @@ int32_t sbuf_share_setup(uint16_t pcpu_id, uint32_t sbuf_id, uint64_t *hva)
 
 	return 0;
 }
+
+void sbuf_reset(uint16_t pcpu_id)
+{
+	uint32_t sbuf_id;
+
+	if (pcpu_id < get_pcpu_nums()) {
+		for (sbuf_id = 0U; sbuf_id < ACRN_SBUF_ID_MAX; sbuf_id++) {
+			per_cpu(sbuf, pcpu_id)[sbuf_id] = 0U;
+		}
+	}
+}
diff --git a/hypervisor/include/debug/sbuf.h b/hypervisor/include/debug/sbuf.h
index 393e39499..3b70062da 100644
--- a/hypervisor/include/debug/sbuf.h
+++ b/hypervisor/include/debug/sbuf.h
@@ -65,6 +65,7 @@ struct shared_buf {
  */
 uint32_t sbuf_put(struct shared_buf *sbuf, uint8_t *data);
 int32_t sbuf_share_setup(uint16_t pcpu_id, uint32_t sbuf_id, uint64_t *hva);
+void sbuf_reset(uint16_t pcpu_id);
 uint32_t sbuf_next_ptr(uint32_t pos, uint32_t span, uint32_t scope);
 
 #endif /* SHARED_BUFFER_H */
diff --git a/hypervisor/release/sbuf.c b/hypervisor/release/sbuf.c
new file mode 100644
index 000000000..fd8dd3386
--- /dev/null
+++ b/hypervisor/release/sbuf.c
@@ -0,0 +1,10 @@
+/*
+ * Copyright (C) 2019 Intel Corporation. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <types.h>
+#include <sbuf.h>
+
+void sbuf_reset(__unused uint16_t pcpu_id) {}