[Xen-devel] [PATCH] xen/arm: p2m: flush TLB by VMID when a new domain is creating

[Julien Grall <julien.grall@xxxxxxxxxx>]

Once the VMID is marked unused, a new domain can reuse the VMID for its
own. If the TLB is not flushed, entries can contain wrong translation.
When a new p2m is allocated, switch to the new VMID and flush TLB on
every physical CPUs.

Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>
---
    Changes in v2:
        - This patch was formerly "xen/arm: p2m: flush TLB when a domain
        is destroyed
        - Flush TLB by VMID in p2m_alloc_table. It will avoid to flush
        all TLBs every domain destruction.

---
 xen/arch/arm/p2m.c                   | 10 ++++++++++
 xen/include/asm-arm/arm32/flushtlb.h | 11 +++++++++++
 xen/include/asm-arm/arm64/flushtlb.h | 11 +++++++++++
 3 files changed, 32 insertions(+)

diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
index 2d09fef..82dda65 100644
--- a/xen/arch/arm/p2m.c
+++ b/xen/arch/arm/p2m.c
@@ -302,6 +302,15 @@ int p2m_alloc_table(struct domain *d)
     d->arch.vttbr = page_to_maddr(p2m->first_level)
         | ((uint64_t)p2m->vmid&0xff)<<48;
 
+    p2m_load_VTTBR(d);
+
+    /* Make sure that all TLBs corresponding to the new VMID are flushed
+     * before using it
+     */
+    flush_tlb();
+
+    p2m_load_VTTBR(current->domain);
+
     spin_unlock(&p2m->lock);
 
     return 0;
@@ -357,6 +366,7 @@ static void p2m_free_vmid(struct domain *d)
     spin_lock(&vmid_alloc_lock);
     if ( p2m->vmid != INVALID_VMID )
         clear_bit(p2m->vmid, vmid_mask);
+
     spin_unlock(&vmid_alloc_lock);
 }
 
diff --git a/xen/include/asm-arm/arm32/flushtlb.h 
b/xen/include/asm-arm/arm32/flushtlb.h
index a258f58..ab166f3 100644
--- a/xen/include/asm-arm/arm32/flushtlb.h
+++ b/xen/include/asm-arm/arm32/flushtlb.h
@@ -12,6 +12,17 @@ static inline void flush_tlb_local(void)
     isb();
 }
 
+/* Flush inner shareable TLBs, current VMID only */
+static inline void flush_tlb(void)
+{
+    dsb();
+
+    WRITE_CP32((uint32_t) 0, TLBIALLIS);
+
+    dsb();
+    isb();
+}
+
 /* Flush local TLBs, all VMIDs, non-hypervisor mode */
 static inline void flush_tlb_all_local(void)
 {
diff --git a/xen/include/asm-arm/arm64/flushtlb.h 
b/xen/include/asm-arm/arm64/flushtlb.h
index d0535a0..9ce79a8 100644
--- a/xen/include/asm-arm/arm64/flushtlb.h
+++ b/xen/include/asm-arm/arm64/flushtlb.h
@@ -12,6 +12,17 @@ static inline void flush_tlb_local(void)
         : : : "memory");
 }
 
+/* Flush innershareable TLBs, current VMID only */
+static inline void flush_tlb(void)
+{
+    asm volatile(
+        "dsb sy;"
+        "tlbi vmalle1is;"
+        "dsb sy;"
+        "isb;"
+        : : : "memory");
+}
+
 /* Flush local TLBs, all VMIDs, non-hypervisor mode */
 static inline void flush_tlb_all_local(void)
 {
-- 
1.8.3.1


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