[Xen-changelog] [xen stable-4.9] xen/arm: Flush TLBs before turning on the MMU to avoid stale entries

[patchbot@xxxxxxx]

commit ad95c2992679b9c2dae7c8bd30439c035f2493de
Author:     Julien Grall <julien.grall@xxxxxxx>
AuthorDate: Tue Feb 27 11:15:57 2018 +0000
Commit:     Stefano Stabellini <sstabellini@xxxxxxxxxx>
CommitDate: Fri Mar 2 15:46:27 2018 -0800

    xen/arm: Flush TLBs before turning on the MMU to avoid stale entries
    
    We don't know what is the state of the TLBs when booting Xen. To avoid
    stale entries, it is necessary to flush the TLBs before turning on the
    MMU.
    
    Reported-by: Iain Hunter <iain@xxxxxxxxxxxxxxxxxxxx>
    Signed-off-by: Julien Grall <julien.gralL@xxxxxxx>
    Acked-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>
    (cherry picked from commit 1c473c42199a8f4d70533c202e1c57ecd1dad35b)
---
 xen/arch/arm/arm32/head.S | 7 +++++++
 xen/arch/arm/arm64/head.S | 7 +++++++
 2 files changed, 14 insertions(+)

diff --git a/xen/arch/arm/arm32/head.S b/xen/arch/arm/arm32/head.S
index 4090f4a744..3fab7b52f9 100644
--- a/xen/arch/arm/arm32/head.S
+++ b/xen/arch/arm/arm32/head.S
@@ -348,6 +348,13 @@ virtphys_clash:
 1:
         PRINT("- Turning on paging -\r\n")
 
+        /*
+         * The state of the TLBs is unknown before turning on the MMU.
+         * Flush them to avoid stale one.
+         */
+        mcr   CP32(r0, TLBIALLH)     /* Flush hypervisor TLBs */
+        dsb   nsh
+
         ldr   r1, =paging            /* Explicit vaddr, not RIP-relative */
         mrc   CP32(r0, HSCTLR)
         orr   r0, r0, #(SCTLR_M|SCTLR_C) /* Enable MMU and D-cache */
diff --git a/xen/arch/arm/arm64/head.S b/xen/arch/arm/arm64/head.S
index 78292f4396..550454471e 100644
--- a/xen/arch/arm/arm64/head.S
+++ b/xen/arch/arm/arm64/head.S
@@ -509,6 +509,13 @@ virtphys_clash:
 1:
         PRINT("- Turning on paging -\r\n")
 
+        /*
+         * The state of the TLBs is unknown before turning on the MMU.
+         * Flush them to avoid stale one.
+         */
+        tlbi  alle2                  /* Flush hypervisor TLBs */
+        dsb   nsh
+
         ldr   x1, =paging            /* Explicit vaddr, not RIP-relative */
         mrs   x0, SCTLR_EL2
         orr   x0, x0, #SCTLR_M       /* Enable MMU */
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.9

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