[Xen-devel,19/20] xen/arm: Pair call to set_fixmap with call to clear_fixmap in copy_from_paddr

Message ID 20190422164937.21350-20-julien.grall@arm.com
State Superseded
Headers show
Series
  • xen/arm: Clean-up & fixes in boot/mm code
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Commit Message

Julien Grall April 22, 2019, 4:49 p.m.
At the moment, set_fixmap may replace a valid entry without following
the break-before-make sequence. This may result to TLB conflict abort.

Rather than dealing with Break-Before-Make in set_fixmap, every call to
set_fixmap is paired with a call to clear_fixmap.

Signed-off-by: Julien Grall <julien.grall@arm.com>
---
 xen/arch/arm/kernel.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

Comments

Andrii Anisov May 3, 2019, 3:59 p.m. | #1
On 22.04.19 19:49, Julien Grall wrote:
> At the moment, set_fixmap may replace a valid entry without following
> the break-before-make sequence. This may result to TLB conflict abort.
> 
> Rather than dealing with Break-Before-Make in set_fixmap, every call to
> set_fixmap is paired with a call to clear_fixmap.
> 
> Signed-off-by: Julien Grall <julien.grall@arm.com>
> ---

Reviewed-by: Andrii Anisov <andrii_anisov@epam.com>

Patch

diff --git a/xen/arch/arm/kernel.c b/xen/arch/arm/kernel.c
index e3ffdb2fa1..389bef2afa 100644
--- a/xen/arch/arm/kernel.c
+++ b/xen/arch/arm/kernel.c
@@ -58,13 +58,12 @@  void __init copy_from_paddr(void *dst, paddr_t paddr, unsigned long len)
         set_fixmap(FIXMAP_MISC, maddr_to_mfn(paddr), PAGE_HYPERVISOR_WC);
         memcpy(dst, src + s, l);
         clean_dcache_va_range(dst, l);
+        clear_fixmap(FIXMAP_MISC);
 
         paddr += l;
         dst += l;
         len -= l;
     }
-
-    clear_fixmap(FIXMAP_MISC);
 }
 
 static void __init place_modules(struct kernel_info *info,