[RFC PATCH 0/1] arm64: 48-bit Physical Address support

[RFC PATCH 0/1] arm64: 48-bit Physical Address support

[mohun106 at gmail.com]

From: Radha Mohan Chintakuntla <rchintakuntla@cavium.com>

This patch adds support for ARMv8 platforms that have 48-bit Physical
Address implemented. The number of levels for translating VA to PA has
not changed.

Radha Mohan Chintakuntla (1):
  arm64: Add support for 48-bit Physical Address

 arch/arm64/Kconfig                     |    3 +++
 arch/arm64/include/asm/kvm_arm.h       |    9 ++++++++-
 arch/arm64/include/asm/pgtable-hwdef.h |   15 +++++++++++++++
 arch/arm64/mm/proc.S                   |    2 +-
 4 files changed, 27 insertions(+), 2 deletions(-)

[RFC PATCH 1/1] arm64: Add support for 48-bit Physical Address

[mohun106 at gmail.com]

From: Radha Mohan Chintakuntla <rchintakuntla@cavium.com>

Added support for ARMv8 platforms that have 48-bit physical address
implemented. There is no change in the VA bits and levels of
translation.

Signed-off-by: Radha Mohan Chintakuntla <rchintakuntla@cavium.com>
---
 arch/arm64/Kconfig                     |    3 +++
 arch/arm64/include/asm/kvm_arm.h       |    9 ++++++++-
 arch/arm64/include/asm/pgtable-hwdef.h |   15 +++++++++++++++
 arch/arm64/mm/proc.S                   |    2 +-
 4 files changed, 27 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 27bbcfc..4494327 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -106,6 +106,9 @@ config IOMMU_HELPER
 config KERNEL_MODE_NEON
 	def_bool y
 
+config ARCH_SUPPORTS_48BIT_PA
+	def_bool n
+
 source "init/Kconfig"
 
 source "kernel/Kconfig.freezer"
diff --git a/arch/arm64/include/asm/kvm_arm.h b/arch/arm64/include/asm/kvm_arm.h
index 0eb3986..214b12d 100644
--- a/arch/arm64/include/asm/kvm_arm.h
+++ b/arch/arm64/include/asm/kvm_arm.h
@@ -107,6 +107,7 @@
 /* VTCR_EL2 Registers bits */
 #define VTCR_EL2_PS_MASK	(7 << 16)
 #define VTCR_EL2_PS_40B		(2 << 16)
+#define VTCR_EL2_PS_48B		(5 << 16)
 #define VTCR_EL2_TG0_MASK	(1 << 14)
 #define VTCR_EL2_TG0_4K		(0 << 14)
 #define VTCR_EL2_TG0_64K	(1 << 14)
@@ -121,6 +122,12 @@
 #define VTCR_EL2_T0SZ_MASK	0x3f
 #define VTCR_EL2_T0SZ_40B	24
 
+#ifdef CONFIG_ARCH_SUPPORTS_48BIT_PA
+#define VTCR_EL2_PS_BITS	VTCR_EL2_PS_48B
+#else
+#define VTCR_EL2_PS_BITS	VTCR_EL2_PS_40B
+#endif
+
 #ifdef CONFIG_ARM64_64K_PAGES
 /*
  * Stage2 translation configuration:
@@ -129,7 +136,7 @@
  * 64kB pages (TG0 = 1)
  * 2 level page tables (SL = 1)
  */
-#define VTCR_EL2_FLAGS		(VTCR_EL2_PS_40B | VTCR_EL2_TG0_64K | \
+#define VTCR_EL2_FLAGS		(VTCR_EL2_PS_BITS | VTCR_EL2_TG0_64K | \
 				 VTCR_EL2_SH0_INNER | VTCR_EL2_ORGN0_WBWA | \
 				 VTCR_EL2_IRGN0_WBWA | VTCR_EL2_SL0_LVL1 | \
 				 VTCR_EL2_T0SZ_40B)
diff --git a/arch/arm64/include/asm/pgtable-hwdef.h b/arch/arm64/include/asm/pgtable-hwdef.h
index b1d2e26..6d93ba6 100644
--- a/arch/arm64/include/asm/pgtable-hwdef.h
+++ b/arch/arm64/include/asm/pgtable-hwdef.h
@@ -99,10 +99,18 @@
 #define PMD_HYP			PMD_SECT_USER
 #define PTE_HYP			PTE_USER
 
+#ifdef CONFIG_ARCH_SUPPORTS_48BIT_PA
+/*
+ * 48-bit physical address supported.
+ */
+#define PHYS_MASK_SHIFT		(48)
+#else
 /*
  * 40-bit physical address supported.
  */
 #define PHYS_MASK_SHIFT		(40)
+#endif
+
 #define PHYS_MASK		((UL(1) << PHYS_MASK_SHIFT) - 1)
 
 /*
@@ -123,7 +131,14 @@
 #define TCR_TG0_64K		(UL(1) << 14)
 #define TCR_TG1_64K		(UL(1) << 30)
 #define TCR_IPS_40BIT		(UL(2) << 32)
+#define TCR_IPS_48BIT		(UL(5) << 32)
 #define TCR_ASID16		(UL(1) << 36)
 #define TCR_TBI0		(UL(1) << 37)
 
+#ifdef CONFIG_ARCH_SUPPORTS_48BIT_PA
+#define TCR_IPS_BITS		TCR_IPS_48BIT
+#else
+#define TCR_IPS_BITS		TCR_IPS_40BIT
+#endif
+
 #endif
diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S
index 1333e6f..3d573a6 100644
--- a/arch/arm64/mm/proc.S
+++ b/arch/arm64/mm/proc.S
@@ -215,7 +215,7 @@ ENTRY(__cpu_setup)
 	 * Set/prepare TCR and TTBR. We use 512GB (39-bit) address range for
 	 * both user and kernel.
 	 */
-	ldr	x10, =TCR_TxSZ(VA_BITS) | TCR_FLAGS | TCR_IPS_40BIT | \
+	ldr	x10, =TCR_TxSZ(VA_BITS) | TCR_FLAGS | TCR_IPS_BITS | \
 		      TCR_ASID16 | TCR_TBI0 | (1 << 31)
 #ifdef CONFIG_ARM64_64K_PAGES
 	orr	x10, x10, TCR_TG0_64K
-- 
1.7.1

[RFC PATCH 1/1] arm64: Add support for 48-bit Physical Address

[Christopher Covington]

Hi Radha,

On 02/26/2014 12:58 AM, mohun106 at gmail.com wrote:
> From: Radha Mohan Chintakuntla <rchintakuntla@cavium.com>
> 
> Added support for ARMv8 platforms that have 48-bit physical address
> implemented. There is no change in the VA bits and levels of
> translation.

Is there benefit to using build-time constants for this information? Why not
look up the physical address range at run time, so that a single kernel binary
could run on any system?

Thanks,
Christopher

-- 
Employee of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
hosted by the Linux Foundation.

[RFC PATCH 1/1] arm64: Add support for 48-bit Physical Address

[Catalin Marinas]

On Wed, Feb 26, 2014 at 01:49:50PM +0000, Christopher Covington wrote:
> On 02/26/2014 12:58 AM, mohun106 at gmail.com wrote:
> > From: Radha Mohan Chintakuntla <rchintakuntla@cavium.com>
> > 
> > Added support for ARMv8 platforms that have 48-bit physical address
> > implemented. There is no change in the VA bits and levels of
> > translation.
> 
> Is there benefit to using build-time constants for this information? Why not
> look up the physical address range at run time, so that a single kernel binary
> could run on any system?

I agree, we don't need a Kconfig option for this, just check the
available (intermediate) physical address bits at boot-time
(ID_AA64MMFR0_EL1) and program the TCR_ELx registers accordingly.

(for whatever reason, I got the same patches in private and I replied
with the same but they haven't been changed before appearing on the
list)

-- 
Catalin

[RFC PATCH 1/1] arm64: Add support for 48-bit Physical Address

[Radha Mohan]

On Wed, Feb 26, 2014 at 7:38 PM, Catalin Marinas
<catalin.marinas@arm.com> wrote:
> On Wed, Feb 26, 2014 at 01:49:50PM +0000, Christopher Covington wrote:
>> On 02/26/2014 12:58 AM, mohun106 at gmail.com wrote:
>> > From: Radha Mohan Chintakuntla <rchintakuntla@cavium.com>
>> >
>> > Added support for ARMv8 platforms that have 48-bit physical address
>> > implemented. There is no change in the VA bits and levels of
>> > translation.
>>
>> Is there benefit to using build-time constants for this information? Why not
>> look up the physical address range at run time, so that a single kernel binary
>> could run on any system?
>
> I agree, we don't need a Kconfig option for this, just check the
> available (intermediate) physical address bits at boot-time
> (ID_AA64MMFR0_EL1) and program the TCR_ELx registers accordingly.
>

OK, I will redo with the proposed changes.

> (for whatever reason, I got the same patches in private and I replied
> with the same but they haven't been changed before appearing on the
> list)
>
Oops, I did miss that mail.

regards,
Radha

> --
> Catalin