[Xen-devel] [PATCH v2 11/25] arm/altp2m: Add HVMOP_altp2m_destroy_p2m.

[Sergej Proskurin <proskurin@xxxxxxxxxxxxx>]

Signed-off-by: Sergej Proskurin <proskurin@xxxxxxxxxxxxx>
---
Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>
Cc: Julien Grall <julien.grall@xxxxxxx>
---
v2: Substituted the call to tlb_flush for p2m_flush_table.
    Added comments.
    Cosmetic fixes.
---
 xen/arch/arm/altp2m.c        | 50 ++++++++++++++++++++++++++++++++++++++++++++
 xen/arch/arm/hvm.c           |  2 +-
 xen/include/asm-arm/altp2m.h |  4 ++++
 3 files changed, 55 insertions(+), 1 deletion(-)

diff --git a/xen/arch/arm/altp2m.c b/xen/arch/arm/altp2m.c
index c22d2e4..80ed553 100644
--- a/xen/arch/arm/altp2m.c
+++ b/xen/arch/arm/altp2m.c
@@ -212,6 +212,56 @@ void altp2m_flush(struct domain *d)
     altp2m_unlock(d);
 }
 
+int altp2m_destroy_by_id(struct domain *d, unsigned int idx)
+{
+    struct p2m_domain *p2m;
+    int rc = -EBUSY;
+
+    /*
+     * The altp2m[0] is considered as the hostp2m and is used as a safe harbor
+     * to which you can switch as long as altp2m is active. After deactivating
+     * altp2m, the system switches back to the original hostp2m view. That is,
+     * altp2m[0] should only be destroyed/flushed/freed, when altp2m is
+     * deactivated.
+     */
+    if ( !idx || idx >= MAX_ALTP2M )
+        return rc;
+
+    domain_pause_except_self(d);
+
+    altp2m_lock(d);
+
+    if ( d->arch.altp2m_vttbr[idx] != INVALID_VTTBR )
+    {
+        p2m = d->arch.altp2m_p2m[idx];
+
+        if ( !_atomic_read(p2m->active_vcpus) )
+        {
+            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[idx] = INVALID_VTTBR;
+
+            read_unlock(&p2m->lock);
+
+            rc = 0;
+        }
+    }
+
+    altp2m_unlock(d);
+
+    domain_unpause_except_self(d);
+
+    return rc;
+}
+
 void altp2m_teardown(struct domain *d)
 {
     unsigned int i;
diff --git a/xen/arch/arm/hvm.c b/xen/arch/arm/hvm.c
index 063a06b..df29cdc 100644
--- a/xen/arch/arm/hvm.c
+++ b/xen/arch/arm/hvm.c
@@ -125,7 +125,7 @@ static int do_altp2m_op(XEN_GUEST_HANDLE_PARAM(void) arg)
         break;
 
     case HVMOP_altp2m_destroy_p2m:
-        rc = -EOPNOTSUPP;
+        rc = altp2m_destroy_by_id(d, a.u.view.view);
         break;
 
     case HVMOP_altp2m_switch_p2m:
diff --git a/xen/include/asm-arm/altp2m.h b/xen/include/asm-arm/altp2m.h
index 3ecae27..afa1580 100644
--- a/xen/include/asm-arm/altp2m.h
+++ b/xen/include/asm-arm/altp2m.h
@@ -60,4 +60,8 @@ int altp2m_init_next(struct domain *d,
 /* Flush all the alternate p2m's for a domain */
 void altp2m_flush(struct domain *d);
 
+/* Make a specific alternate p2m invalid */
+int altp2m_destroy_by_id(struct domain *d,
+                         unsigned int idx);
+
 #endif /* __ASM_ARM_ALTP2M_H */
-- 
2.9.0


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
https://lists.xen.org/xen-devel