[Xen-devel] [PATCH v2 09/25] arm/altp2m: 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 flush all or individual altp2m views without destroying
the entire table. In this way, altp2m views can be reused at a later
point in time.

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.
---
 xen/arch/arm/altp2m.c        | 38 ++++++++++++++++++++++++++++++++++++++
 xen/include/asm-arm/altp2m.h |  5 +----
 xen/include/asm-arm/p2m.h    |  3 +++
 3 files changed, 42 insertions(+), 4 deletions(-)

diff --git a/xen/arch/arm/altp2m.c b/xen/arch/arm/altp2m.c
index 767f233..e73424c 100644
--- a/xen/arch/arm/altp2m.c
+++ b/xen/arch/arm/altp2m.c
@@ -151,6 +151,44 @@ 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_vttbr[i] == INVALID_VTTBR )
+            continue;
+
+        p2m = d->arch.altp2m_p2m[i];
+
+        read_lock(&p2m->lock);
+
+        p2m_flush_table(p2m);
+
+        /*
+         * Reset VTTBR.
+         *
+         * Note that VMID is not freed so that it can be reused later.
+         */
+        p2m->vttbr.vttbr = INVALID_VTTBR;
+        d->arch.altp2m_vttbr[i] = INVALID_VTTBR;
+
+        read_unlock(&p2m->lock);
+    }
+
+    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 a33c740..3ba82a8 100644
--- a/xen/include/asm-arm/altp2m.h
+++ b/xen/include/asm-arm/altp2m.h
@@ -54,9 +54,6 @@ int altp2m_init_by_id(struct domain *d,
                       unsigned int idx);
 
 /* Flush all the alternate p2m's for a domain */
-static inline void altp2m_flush(struct domain *d)
-{
-    /* Not yet implemented. */
-}
+void altp2m_flush(struct domain *d);
 
 #endif /* __ASM_ARM_ALTP2M_H */
diff --git a/xen/include/asm-arm/p2m.h b/xen/include/asm-arm/p2m.h
index f13f285..32326cb 100644
--- a/xen/include/asm-arm/p2m.h
+++ b/xen/include/asm-arm/p2m.h
@@ -222,6 +222,9 @@ mfn_t gfn_to_mfn(struct domain *d, gfn_t gfn);
 /* Allocates page table for a p2m. */
 int p2m_alloc_table(struct p2m_domain *p2m);
 
+/* Flushes the page table held by the p2m. */
+void p2m_flush_table(struct p2m_domain *p2m);
+
 /* Initialize the p2m structure. */
 int p2m_init_one(struct domain *d, struct p2m_domain *p2m);
 
-- 
2.9.0


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