[PATCH] arm64: mm: Ensure writes to swapper are ordered wrt subsequent cache maintenance
When rewriting swapper using nG mappings, we must performance cache maintenance around each page table access in order to avoid coherency problems with the host's cacheable alias under KVM. To ensure correct ordering of the maintenance with respect to Device memory accesses made with the Stage-1 MMU disabled, DMBs need to be added between the maintenance and the corresponding memory access.
This patch adds a missing DMB between writing a new page table entry and performing a clean+invalidate on the same line.
Cc: stable@vger.kernel.org Signed-off-by: Will Deacon will.deacon@arm.com --- arch/arm64/mm/proc.S | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S index 5f9a73a4452c..03646e6a2ef4 100644 --- a/arch/arm64/mm/proc.S +++ b/arch/arm64/mm/proc.S @@ -217,8 +217,9 @@ ENDPROC(idmap_cpu_replace_ttbr1)
.macro __idmap_kpti_put_pgtable_ent_ng, type orr \type, \type, #PTE_NG // Same bit for blocks and pages - str \type, [cur_()\type()p] // Update the entry and ensure it - dc civac, cur_()\type()p // is visible to all CPUs. + str \type, [cur_()\type()p] // Update the entry and ensure + dmb sy // that it is visible to all + dc civac, cur_()\type()p // CPUs. .endm
/*
On Fri, Jun 22, 2018 at 04:23:45PM +0100, Will Deacon wrote:
When rewriting swapper using nG mappings, we must performance cache maintenance around each page table access in order to avoid coherency problems with the host's cacheable alias under KVM. To ensure correct ordering of the maintenance with respect to Device memory accesses made with the Stage-1 MMU disabled, DMBs need to be added between the maintenance and the corresponding memory access.
This patch adds a missing DMB between writing a new page table entry and performing a clean+invalidate on the same line.
Cc: stable@vger.kernel.org Signed-off-by: Will Deacon will.deacon@arm.com
Acked-by: Mark Rutland mark.rutland@arm.com
Mark.
arch/arm64/mm/proc.S | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S index 5f9a73a4452c..03646e6a2ef4 100644 --- a/arch/arm64/mm/proc.S +++ b/arch/arm64/mm/proc.S @@ -217,8 +217,9 @@ ENDPROC(idmap_cpu_replace_ttbr1) .macro __idmap_kpti_put_pgtable_ent_ng, type orr \type, \type, #PTE_NG // Same bit for blocks and pages
- str \type, [cur_()\type()p] // Update the entry and ensure it
- dc civac, cur_()\type()p // is visible to all CPUs.
- str \type, [cur_()\type()p] // Update the entry and ensure
- dmb sy // that it is visible to all
- dc civac, cur_()\type()p // CPUs. .endm
/* -- 2.1.4
On Fri, Jun 22, 2018 at 04:23:45PM +0100, Will Deacon wrote:
When rewriting swapper using nG mappings, we must performance cache maintenance around each page table access in order to avoid coherency problems with the host's cacheable alias under KVM. To ensure correct ordering of the maintenance with respect to Device memory accesses made with the Stage-1 MMU disabled, DMBs need to be added between the maintenance and the corresponding memory access.
This patch adds a missing DMB between writing a new page table entry and performing a clean+invalidate on the same line.
Cc: stable@vger.kernel.org Signed-off-by: Will Deacon will.deacon@arm.com
Applied. Thanks.
linux-stable-mirror@lists.linaro.org
-
Catalin Marinas -
Mark Rutland -
Will Deacon