[Xen-devel] [PATCH] xen/arm: p2m: Correctly flush TLB in create_p2m_entries

[Julien Grall <julien.grall@xxxxxxxxxx>]

The p2m is shared between VCPUs for each domain. Currently Xen only flush
TLB on the local PCPU. This could result to mismatch between the mapping in the
p2m and TLBs.

Flush TLBs used by this domain on every PCPU.

Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>

---

This is a possible bug fix (found by reading the code) for Xen 4.4. I have
added a small optimisation to avoid flushing all TLBs when a VCPU of this
domain is running on the current cpu.

The downside of this patch is the function can be a little bit slower because
Xen is flushing more TLBs.
---
 xen/arch/arm/p2m.c                   |    7 ++++++-
 xen/include/asm-arm/arm32/flushtlb.h |    6 +++---
 xen/include/asm-arm/arm64/flushtlb.h |    6 +++---
 3 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
index 11f4714..9ab0378 100644
--- a/xen/arch/arm/p2m.c
+++ b/xen/arch/arm/p2m.c
@@ -374,7 +374,12 @@ static int create_p2m_entries(struct domain *d,
         }
 
         if ( flush )
-            flush_tlb_all_local();
+        {
+            if ( current->domain == d )
+                flush_tlb();
+            else
+                flush_tlb_all();
+        }
 
         /* Preempt every 2MiB (mapped) or 32 MiB (unmapped) - arbitrary */
         if ( op == RELINQUISH && count >= 0x2000 )
diff --git a/xen/include/asm-arm/arm32/flushtlb.h 
b/xen/include/asm-arm/arm32/flushtlb.h
index ab166f3..6ff6f75 100644
--- a/xen/include/asm-arm/arm32/flushtlb.h
+++ b/xen/include/asm-arm/arm32/flushtlb.h
@@ -23,12 +23,12 @@ static inline void flush_tlb(void)
     isb();
 }
 
-/* Flush local TLBs, all VMIDs, non-hypervisor mode */
-static inline void flush_tlb_all_local(void)
+/* Flush inner shareable TLBs, all VMIDs, non-hypervisor mode */
+static inline void flush_tlb_all(void)
 {
     dsb();
 
-    WRITE_CP32((uint32_t) 0, TLBIALLNSNH);
+    WRITE_CP32((uint32_t) 0, TLBIALLNSNHIS);
 
     dsb();
     isb();
diff --git a/xen/include/asm-arm/arm64/flushtlb.h 
b/xen/include/asm-arm/arm64/flushtlb.h
index 9ce79a8..687eda1 100644
--- a/xen/include/asm-arm/arm64/flushtlb.h
+++ b/xen/include/asm-arm/arm64/flushtlb.h
@@ -23,12 +23,12 @@ static inline void flush_tlb(void)
         : : : "memory");
 }
 
-/* Flush local TLBs, all VMIDs, non-hypervisor mode */
-static inline void flush_tlb_all_local(void)
+/* Flush inner shareable TLBs, all VMIDs, non-hypervisor mode */
+static inline void flush_tlb_all(void)
 {
     asm volatile(
         "dsb sy;"
-        "tlbi alle1;"
+        "tlbi alle1is;"
         "dsb sy;"
         "isb;"
         : : : "memory");
-- 
1.7.10.4


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