[Xen-devel] [PATCH v3 15/38] arm/p2m: Add altp2m table flushing routine

[Sergej Proskurin <proskurin@xxxxxxxxxxxxx>]

The current implementation differentiates between flushing and
destroying altp2m views. This commit adds the function altp2m_flush,
which allows to release all of the alternate p2m views.

Signed-off-by: Sergej Proskurin <proskurin@xxxxxxxxxxxxx>
---
Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>
Cc: Julien Grall <julien.grall@xxxxxxx>
---
v2: Pages in p2m->pages are not cleared in p2m_flush_table anymore.
    VMID is freed in p2m_free_one.
    Cosmetic fixes.

v3: Changed the locking mechanism to "p2m_write_lock" inside the
    function "altp2m_flush".

    Do not flush but rather teardown the altp2m in the function
    "altp2m_flush".

    Exchanged the check "altp2m_vttbr[idx] == INVALID_VTTBR" for
    "altp2m_p2m[idx] == NULL" in "altp2m_flush".
---
 xen/arch/arm/altp2m.c        | 31 +++++++++++++++++++++++++++++++
 xen/include/asm-arm/altp2m.h |  3 +++
 2 files changed, 34 insertions(+)

diff --git a/xen/arch/arm/altp2m.c b/xen/arch/arm/altp2m.c
index 66a373a..02cffd7 100644
--- a/xen/arch/arm/altp2m.c
+++ b/xen/arch/arm/altp2m.c
@@ -34,6 +34,37 @@ int altp2m_init(struct domain *d)
     return 0;
 }
 
+void altp2m_flush(struct domain *d)
+{
+    unsigned int i;
+    struct p2m_domain *p2m;
+
+    /*
+     * If altp2m is active, we are not allowed to flush altp2m[0]. This special
+     * view is considered as the hostp2m as long as altp2m is active.
+     */
+    ASSERT(!altp2m_active(d));
+
+    altp2m_lock(d);
+
+    for ( i = 0; i < MAX_ALTP2M; i++ )
+    {
+        if ( d->arch.altp2m_p2m[i] == NULL )
+            continue;
+
+        p2m = d->arch.altp2m_p2m[i];
+
+        p2m_write_lock(p2m);
+        p2m_teardown_one(p2m);
+        p2m_write_unlock(p2m);
+
+        xfree(p2m);
+        d->arch.altp2m_p2m[i] = NULL;
+    }
+
+    altp2m_unlock(d);
+}
+
 void altp2m_teardown(struct domain *d)
 {
     unsigned int i;
diff --git a/xen/include/asm-arm/altp2m.h b/xen/include/asm-arm/altp2m.h
index a156109..4c15b75 100644
--- a/xen/include/asm-arm/altp2m.h
+++ b/xen/include/asm-arm/altp2m.h
@@ -42,4 +42,7 @@ static inline uint16_t altp2m_vcpu_idx(const struct vcpu *v)
 int altp2m_init(struct domain *d);
 void altp2m_teardown(struct domain *d);
 
+/* Flush all the alternate p2m's for a domain. */
+void altp2m_flush(struct domain *d);
+
 #endif /* __ASM_ARM_ALTP2M_H */
-- 
2.9.0


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