[PATCH] KVM: arm64: Fix definition of PAGE_HYP_DEVICE

[PATCH] KVM: arm64: Fix definition of PAGE_HYP_DEVICE

[Will Deacon]

PAGE_HYP_DEVICE is intended to encode attribute bits for an EL2 stage-1
pte mapping a device. Unfortunately, it includes PROT_DEVICE_nGnRE which
encodes attributes for EL1 stage-1 mappings such as UXN and nG, which are
RES0 for EL2, and DBM which is meaningless as TCR_EL2.HD is not set.

Fix the definition of PAGE_HYP_DEVICE so that it doesn't set RES0 bits
at EL2.

Cc: Marc Zyngier <maz@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Will Deacon <will@kernel.org>
---
Marc -- I'm happy to take this as a fix via arm64 with your Ack.
Please just let me know.

 arch/arm64/include/asm/pgtable-prot.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/include/asm/pgtable-prot.h b/arch/arm64/include/asm/pgtable-prot.h
index 2e7e0f452301..4d867c6446c4 100644
--- a/arch/arm64/include/asm/pgtable-prot.h
+++ b/arch/arm64/include/asm/pgtable-prot.h
@@ -67,7 +67,7 @@ extern bool arm64_use_ng_mappings;
 #define PAGE_HYP		__pgprot(_HYP_PAGE_DEFAULT | PTE_HYP | PTE_HYP_XN)
 #define PAGE_HYP_EXEC		__pgprot(_HYP_PAGE_DEFAULT | PTE_HYP | PTE_RDONLY)
 #define PAGE_HYP_RO		__pgprot(_HYP_PAGE_DEFAULT | PTE_HYP | PTE_RDONLY | PTE_HYP_XN)
-#define PAGE_HYP_DEVICE		__pgprot(PROT_DEVICE_nGnRE | PTE_HYP)
+#define PAGE_HYP_DEVICE		__pgprot(_PROT_DEFAULT | PTE_ATTRINDX(MT_DEVICE_nGnRE) | PTE_HYP | PTE_HYP_XN)
 
 #define PAGE_S2_MEMATTR(attr)						\
 	({								\
-- 
2.27.0.383.g050319c2ae-goog

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Re: [PATCH] KVM: arm64: Fix definition of PAGE_HYP_DEVICE

[Marc Zyngier]

On 2020-07-08 17:25, Will Deacon wrote:
> PAGE_HYP_DEVICE is intended to encode attribute bits for an EL2 stage-1
> pte mapping a device. Unfortunately, it includes PROT_DEVICE_nGnRE 
> which
> encodes attributes for EL1 stage-1 mappings such as UXN and nG, which 
> are
> RES0 for EL2, and DBM which is meaningless as TCR_EL2.HD is not set.
> 
> Fix the definition of PAGE_HYP_DEVICE so that it doesn't set RES0 bits
> at EL2.
> 
> Cc: Marc Zyngier <maz@kernel.org>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: James Morse <james.morse@arm.com>
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Will Deacon <will@kernel.org>
> ---
> Marc -- I'm happy to take this as a fix via arm64 with your Ack.
> Please just let me know.
> 
>  arch/arm64/include/asm/pgtable-prot.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Acked-by: Marc Zyngier <maz@kernel.org>

Thanks for fixing this!

         M.
-- 
Jazz is not dead. It just smells funny...
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Re: [PATCH] KVM: arm64: Fix definition of PAGE_HYP_DEVICE

[Will Deacon]

On Wed, 8 Jul 2020 17:25:46 +0100, Will Deacon wrote:
> PAGE_HYP_DEVICE is intended to encode attribute bits for an EL2 stage-1
> pte mapping a device. Unfortunately, it includes PROT_DEVICE_nGnRE which
> encodes attributes for EL1 stage-1 mappings such as UXN and nG, which are
> RES0 for EL2, and DBM which is meaningless as TCR_EL2.HD is not set.
> 
> Fix the definition of PAGE_HYP_DEVICE so that it doesn't set RES0 bits
> at EL2.

Applied to arm64 (for-next/fixes), thanks!

[1/1] KVM: arm64: Fix definition of PAGE_HYP_DEVICE
      https://git.kernel.org/arm64/c/68cf617309b5

Cheers,
-- 
Will

https://fixes.arm64.dev
https://next.arm64.dev
https://will.arm64.dev
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