[Xen-devel] [PATCH] xen/arm: correct flush_tlb_mask behaviour

[Julien Grall <julien.grall@xxxxxxxxxx>]

On ARM, flush_tlb_mask is used in the common code:
    - alloc_heap_pages: the flush is only be called if the new allocated
    page was used by a domain before. So we need to flush only TLB non-secure
non-hyp inner-shareable.
    - common/grant-table.c: every calls to flush_tlb_mask are used with
    the current domain. A flush TLB by current VMID inner-shareable is enough.

The current code only flush hypervisor TLB on the current PCPU. For now,
flush TLBs non-secure non-hyp on every PCPUs.

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

---
    This patch is bug fix for Xen 4.4. We were safe because there is already
a flush in create_p2m_entries if the previous mapping was valid.

For Xen 4.5, we should optimize the function to avoid flush for every VMIDs
each time we allocated a new page.
---
 xen/arch/arm/smp.c                   |    3 ++-
 xen/include/asm-arm/arm32/flushtlb.h |   11 +++++++++++
 xen/include/asm-arm/arm64/flushtlb.h |   11 +++++++++++
 3 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/xen/arch/arm/smp.c b/xen/arch/arm/smp.c
index 4042db5..30203b8 100644
--- a/xen/arch/arm/smp.c
+++ b/xen/arch/arm/smp.c
@@ -4,11 +4,12 @@
 #include <asm/cpregs.h>
 #include <asm/page.h>
 #include <asm/gic.h>
+#include <asm/flushtlb.h>
 
 void flush_tlb_mask(const cpumask_t *mask)
 {
     /* No need to IPI other processors on ARM, the processor takes care of it. 
*/
-    flush_xen_data_tlb();
+    flush_tlb_all();
 }
 
 void smp_send_event_check_mask(const cpumask_t *mask)
diff --git a/xen/include/asm-arm/arm32/flushtlb.h 
b/xen/include/asm-arm/arm32/flushtlb.h
index ab166f3..7183a07 100644
--- a/xen/include/asm-arm/arm32/flushtlb.h
+++ b/xen/include/asm-arm/arm32/flushtlb.h
@@ -34,6 +34,17 @@ static inline void flush_tlb_all_local(void)
     isb();
 }
 
+/* Flush innershareable TLBs, all VMIDs, non-hypervisor mode */
+static inline void flush_tlb_all(void)
+{
+    dsb();
+
+    WRITE_CP32((uint32_t) 0, TLBIALLNSNHIS);
+
+    dsb();
+    isb();
+}
+
 #endif /* __ASM_ARM_ARM32_FLUSHTLB_H__ */
 /*
  * Local variables:
diff --git a/xen/include/asm-arm/arm64/flushtlb.h 
b/xen/include/asm-arm/arm64/flushtlb.h
index 9ce79a8..a73df92 100644
--- a/xen/include/asm-arm/arm64/flushtlb.h
+++ b/xen/include/asm-arm/arm64/flushtlb.h
@@ -34,6 +34,17 @@ static inline void flush_tlb_all_local(void)
         : : : "memory");
 }
 
+/* Flush innershareable TLBs, all VMIDs, non-hypervisor mode */
+static inline void flush_tlb_all(void)
+{
+    asm volatile(
+        "dsb sy;"
+        "tlbi alle1is;"
+        "dsb sy;"
+        "isb;"
+        : : : "memory");
+}
+
 #endif /* __ASM_ARM_ARM64_FLUSHTLB_H__ */
 /*
  * Local variables:
-- 
1.7.10.4


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