[PATCH V2] arm64/mm: Fix __enable_mmu() for new TGRAN range values

[PATCH V2] arm64/mm: Fix __enable_mmu() for new TGRAN range values

[Anshuman Khandual]

From: James Morse <james.morse@arm.com>

As per ARM ARM DDI 0487G.a, when FEAT_LPA2 is implemented, ID_AA64MMFR0_EL1
might contain a range of values to describe supported translation granules
(4K and 16K pages sizes in particular) instead of just enabled or disabled
values. This changes __enable_mmu() function to handle complete acceptable
range of values (depending on whether the field is signed or unsigned) now
represented with ID_AA64MMFR0_TGRAN_SUPPORTED_[MIN..MAX] pair. While here,
also fix similar situations in EFI stub and KVM as well.

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Marc Zyngier <maz@kernel.org>
Cc: James Morse <james.morse@arm.com>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: kvmarm@lists.cs.columbia.edu
Cc: linux-efi@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Acked-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
---
Changes in V2:

- Changes back to switch construct in kvm_set_ipa_limit() per Marc

Changes in V1:

https://patchwork.kernel.org/project/linux-arm-kernel/list/?series=442817

 arch/arm64/include/asm/sysreg.h           | 20 ++++++++++++++------
 arch/arm64/kernel/head.S                  |  6 ++++--
 arch/arm64/kvm/reset.c                    | 10 ++++++----
 drivers/firmware/efi/libstub/arm64-stub.c |  2 +-
 4 files changed, 25 insertions(+), 13 deletions(-)

diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h
index dfd4edb..d4a5fca9 100644
--- a/arch/arm64/include/asm/sysreg.h
+++ b/arch/arm64/include/asm/sysreg.h
@@ -796,6 +796,11 @@
 #define ID_AA64MMFR0_PARANGE_48		0x5
 #define ID_AA64MMFR0_PARANGE_52		0x6
 
+#define ID_AA64MMFR0_TGRAN_2_SUPPORTED_DEFAULT	0x0
+#define ID_AA64MMFR0_TGRAN_2_SUPPORTED_NONE	0x1
+#define ID_AA64MMFR0_TGRAN_2_SUPPORTED_MIN	0x2
+#define ID_AA64MMFR0_TGRAN_2_SUPPORTED_MAX	0x7
+
 #ifdef CONFIG_ARM64_PA_BITS_52
 #define ID_AA64MMFR0_PARANGE_MAX	ID_AA64MMFR0_PARANGE_52
 #else
@@ -961,14 +966,17 @@
 #define ID_PFR1_PROGMOD_SHIFT		0
 
 #if defined(CONFIG_ARM64_4K_PAGES)
-#define ID_AA64MMFR0_TGRAN_SHIFT	ID_AA64MMFR0_TGRAN4_SHIFT
-#define ID_AA64MMFR0_TGRAN_SUPPORTED	ID_AA64MMFR0_TGRAN4_SUPPORTED
+#define ID_AA64MMFR0_TGRAN_SHIFT		ID_AA64MMFR0_TGRAN4_SHIFT
+#define ID_AA64MMFR0_TGRAN_SUPPORTED_MIN	ID_AA64MMFR0_TGRAN4_SUPPORTED
+#define ID_AA64MMFR0_TGRAN_SUPPORTED_MAX	0x7
 #elif defined(CONFIG_ARM64_16K_PAGES)
-#define ID_AA64MMFR0_TGRAN_SHIFT	ID_AA64MMFR0_TGRAN16_SHIFT
-#define ID_AA64MMFR0_TGRAN_SUPPORTED	ID_AA64MMFR0_TGRAN16_SUPPORTED
+#define ID_AA64MMFR0_TGRAN_SHIFT		ID_AA64MMFR0_TGRAN16_SHIFT
+#define ID_AA64MMFR0_TGRAN_SUPPORTED_MIN	ID_AA64MMFR0_TGRAN16_SUPPORTED
+#define ID_AA64MMFR0_TGRAN_SUPPORTED_MAX	0xF
 #elif defined(CONFIG_ARM64_64K_PAGES)
-#define ID_AA64MMFR0_TGRAN_SHIFT	ID_AA64MMFR0_TGRAN64_SHIFT
-#define ID_AA64MMFR0_TGRAN_SUPPORTED	ID_AA64MMFR0_TGRAN64_SUPPORTED
+#define ID_AA64MMFR0_TGRAN_SHIFT		ID_AA64MMFR0_TGRAN64_SHIFT
+#define ID_AA64MMFR0_TGRAN_SUPPORTED_MIN	ID_AA64MMFR0_TGRAN64_SUPPORTED
+#define ID_AA64MMFR0_TGRAN_SUPPORTED_MAX	0x7
 #endif
 
 #define MVFR2_FPMISC_SHIFT		4
diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
index 66b0e0b..8b469f1 100644
--- a/arch/arm64/kernel/head.S
+++ b/arch/arm64/kernel/head.S
@@ -655,8 +655,10 @@ SYM_FUNC_END(__secondary_too_slow)
 SYM_FUNC_START(__enable_mmu)
 	mrs	x2, ID_AA64MMFR0_EL1
 	ubfx	x2, x2, #ID_AA64MMFR0_TGRAN_SHIFT, 4
-	cmp	x2, #ID_AA64MMFR0_TGRAN_SUPPORTED
-	b.ne	__no_granule_support
+	cmp     x2, #ID_AA64MMFR0_TGRAN_SUPPORTED_MIN
+	b.lt    __no_granule_support
+	cmp     x2, #ID_AA64MMFR0_TGRAN_SUPPORTED_MAX
+	b.gt    __no_granule_support
 	update_early_cpu_boot_status 0, x2, x3
 	adrp	x2, idmap_pg_dir
 	phys_to_ttbr x1, x1
diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c
index 47f3f03..e81c7ec 100644
--- a/arch/arm64/kvm/reset.c
+++ b/arch/arm64/kvm/reset.c
@@ -311,16 +311,18 @@ int kvm_set_ipa_limit(void)
 	}
 
 	switch (cpuid_feature_extract_unsigned_field(mmfr0, tgran_2)) {
-	default:
-	case 1:
+	case ID_AA64MMFR0_TGRAN_2_SUPPORTED_NONE:
 		kvm_err("PAGE_SIZE not supported at Stage-2, giving up\n");
 		return -EINVAL;
-	case 0:
+	case ID_AA64MMFR0_TGRAN_2_SUPPORTED_DEFAULT:
 		kvm_debug("PAGE_SIZE supported at Stage-2 (default)\n");
 		break;
-	case 2:
+	case ID_AA64MMFR0_TGRAN_2_SUPPORTED_MIN ... ID_AA64MMFR0_TGRAN_2_SUPPORTED_MAX:
 		kvm_debug("PAGE_SIZE supported at Stage-2 (advertised)\n");
 		break;
+	default:
+		kvm_err("Unsupported value for TGRAN_2, giving up\n");
+		return -EINVAL;
 	}
 
 	kvm_ipa_limit = id_aa64mmfr0_parange_to_phys_shift(parange);
diff --git a/drivers/firmware/efi/libstub/arm64-stub.c b/drivers/firmware/efi/libstub/arm64-stub.c
index b69d631..7bf0a7a 100644
--- a/drivers/firmware/efi/libstub/arm64-stub.c
+++ b/drivers/firmware/efi/libstub/arm64-stub.c
@@ -24,7 +24,7 @@ efi_status_t check_platform_features(void)
 		return EFI_SUCCESS;
 
 	tg = (read_cpuid(ID_AA64MMFR0_EL1) >> ID_AA64MMFR0_TGRAN_SHIFT) & 0xf;
-	if (tg != ID_AA64MMFR0_TGRAN_SUPPORTED) {
+	if (tg < ID_AA64MMFR0_TGRAN_SUPPORTED_MIN || tg > ID_AA64MMFR0_TGRAN_SUPPORTED_MAX) {
 		if (IS_ENABLED(CONFIG_ARM64_64K_PAGES))
 			efi_err("This 64 KB granular kernel is not supported by your CPU\n");
 		else
-- 
2.7.4

Re: [PATCH V2] arm64/mm: Fix __enable_mmu() for new TGRAN range values

[Will Deacon]

On Wed, 10 Mar 2021 11:23:10 +0530, Anshuman Khandual wrote:
> As per ARM ARM DDI 0487G.a, when FEAT_LPA2 is implemented, ID_AA64MMFR0_EL1
> might contain a range of values to describe supported translation granules
> (4K and 16K pages sizes in particular) instead of just enabled or disabled
> values. This changes __enable_mmu() function to handle complete acceptable
> range of values (depending on whether the field is signed or unsigned) now
> represented with ID_AA64MMFR0_TGRAN_SUPPORTED_[MIN..MAX] pair. While here,
> also fix similar situations in EFI stub and KVM as well.

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

[1/1] arm64/mm: Fix __enable_mmu() for new TGRAN range values
      https://git.kernel.org/arm64/c/26f55386f964

Cheers,
-- 
Will

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

Re: [PATCH V2] arm64/mm: Fix __enable_mmu() for new TGRAN range values

[Anders Roxell]

On 2021-03-10 11:23, Anshuman Khandual wrote:
> From: James Morse <james.morse@arm.com>
> 
> As per ARM ARM DDI 0487G.a, when FEAT_LPA2 is implemented, ID_AA64MMFR0_EL1
> might contain a range of values to describe supported translation granules
> (4K and 16K pages sizes in particular) instead of just enabled or disabled
> values. This changes __enable_mmu() function to handle complete acceptable
> range of values (depending on whether the field is signed or unsigned) now
> represented with ID_AA64MMFR0_TGRAN_SUPPORTED_[MIN..MAX] pair. While here,
> also fix similar situations in EFI stub and KVM as well.
> 
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Will Deacon <will@kernel.org>
> Cc: Marc Zyngier <maz@kernel.org>
> Cc: James Morse <james.morse@arm.com>
> Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
> Cc: Ard Biesheuvel <ardb@kernel.org>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Cc: linux-arm-kernel@lists.infradead.org
> Cc: kvmarm@lists.cs.columbia.edu
> Cc: linux-efi@vger.kernel.org
> Cc: linux-kernel@vger.kernel.org
> Acked-by: Marc Zyngier <maz@kernel.org>
> Signed-off-by: James Morse <james.morse@arm.com>
> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>

Hi,

When building an arm64 defconfig kernel from stable/linux-5.10.y and
booting that in QEMU (version: 1:7.0+dfsg-2~bpo11+2) with '-cpu max' the
kernel doesn't boot. I don't get any output.  The kernel boots fine if I
change to '-cpu cortex-a72'.

If I cherry-pick this patch to stable/linux-5.10.y I'm able too boot the
kernel with '-cpu max'.

However, I'm not comfortable to backport this patch to older kernels
since there are a lot of conflicts.
Can someone help out to do the packport?

Cheers,
Anders

Re: [PATCH V2] arm64/mm: Fix __enable_mmu() for new TGRAN range values

[Zenghui Yu]

On 2022/8/26 20:00, Anders Roxell wrote:
> On 2021-03-10 11:23, Anshuman Khandual wrote:
>> From: James Morse <james.morse@arm.com>
>>
>> As per ARM ARM DDI 0487G.a, when FEAT_LPA2 is implemented, ID_AA64MMFR0_EL1
>> might contain a range of values to describe supported translation granules
>> (4K and 16K pages sizes in particular) instead of just enabled or disabled
>> values. This changes __enable_mmu() function to handle complete acceptable
>> range of values (depending on whether the field is signed or unsigned) now
>> represented with ID_AA64MMFR0_TGRAN_SUPPORTED_[MIN..MAX] pair. While here,
>> also fix similar situations in EFI stub and KVM as well.
>>
>> Cc: Catalin Marinas <catalin.marinas@arm.com>
>> Cc: Will Deacon <will@kernel.org>
>> Cc: Marc Zyngier <maz@kernel.org>
>> Cc: James Morse <james.morse@arm.com>
>> Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
>> Cc: Ard Biesheuvel <ardb@kernel.org>
>> Cc: Mark Rutland <mark.rutland@arm.com>
>> Cc: linux-arm-kernel@lists.infradead.org
>> Cc: kvmarm@lists.cs.columbia.edu
>> Cc: linux-efi@vger.kernel.org
>> Cc: linux-kernel@vger.kernel.org
>> Acked-by: Marc Zyngier <maz@kernel.org>
>> Signed-off-by: James Morse <james.morse@arm.com>
>> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
> 
> Hi,
> 
> When building an arm64 defconfig kernel from stable/linux-5.10.y and
> booting that in QEMU (version: 1:7.0+dfsg-2~bpo11+2) with '-cpu max' the
> kernel doesn't boot. I don't get any output.  The kernel boots fine if I
> change to '-cpu cortex-a72'.
> 
> If I cherry-pick this patch to stable/linux-5.10.y I'm able too boot the
> kernel with '-cpu max'.

You can workaround the kernel boot failure by specifying
'-cpu max,lpa2=off' [*] in the QEMU command line.

> However, I'm not comfortable to backport this patch to older kernels
> since there are a lot of conflicts.
> Can someone help out to do the packport?

Upstream commit 26f55386f964 ("arm64/mm: Fix __enable_mmu() for new
TGRAN range values") can still be applied cleanly on top of
linux-5.10.y. I can send it to <stable@vger.kernel.org> if maintainers
are okay with the stable-5.10 backport.

[*] https://gitlab.com/qemu-project/qemu/-/commit/69b2265d5fe8

Zenghui

Re: [PATCH V2] arm64/mm: Fix __enable_mmu() for new TGRAN range values

[Catalin Marinas]

On Fri, Oct 28, 2022 at 10:18:41AM +0800, Zenghui Yu wrote:
> On 2022/8/26 20:00, Anders Roxell wrote:
> > On 2021-03-10 11:23, Anshuman Khandual wrote:
> > > From: James Morse <james.morse@arm.com>
> > > 
> > > As per ARM ARM DDI 0487G.a, when FEAT_LPA2 is implemented, ID_AA64MMFR0_EL1
> > > might contain a range of values to describe supported translation granules
> > > (4K and 16K pages sizes in particular) instead of just enabled or disabled
> > > values. This changes __enable_mmu() function to handle complete acceptable
> > > range of values (depending on whether the field is signed or unsigned) now
> > > represented with ID_AA64MMFR0_TGRAN_SUPPORTED_[MIN..MAX] pair. While here,
> > > also fix similar situations in EFI stub and KVM as well.
> > > 
> > > Cc: Catalin Marinas <catalin.marinas@arm.com>
> > > Cc: Will Deacon <will@kernel.org>
> > > Cc: Marc Zyngier <maz@kernel.org>
> > > Cc: James Morse <james.morse@arm.com>
> > > Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
> > > Cc: Ard Biesheuvel <ardb@kernel.org>
> > > Cc: Mark Rutland <mark.rutland@arm.com>
> > > Cc: linux-arm-kernel@lists.infradead.org
> > > Cc: kvmarm@lists.cs.columbia.edu
> > > Cc: linux-efi@vger.kernel.org
> > > Cc: linux-kernel@vger.kernel.org
> > > Acked-by: Marc Zyngier <maz@kernel.org>
> > > Signed-off-by: James Morse <james.morse@arm.com>
> > > Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
> > 
> > When building an arm64 defconfig kernel from stable/linux-5.10.y and
> > booting that in QEMU (version: 1:7.0+dfsg-2~bpo11+2) with '-cpu max' the
> > kernel doesn't boot. I don't get any output.  The kernel boots fine if I
> > change to '-cpu cortex-a72'.
> > 
> > If I cherry-pick this patch to stable/linux-5.10.y I'm able too boot the
> > kernel with '-cpu max'.
> 
> You can workaround the kernel boot failure by specifying
> '-cpu max,lpa2=off' [*] in the QEMU command line.
> 
> > However, I'm not comfortable to backport this patch to older kernels
> > since there are a lot of conflicts.
> > Can someone help out to do the packport?
> 
> Upstream commit 26f55386f964 ("arm64/mm: Fix __enable_mmu() for new
> TGRAN range values") can still be applied cleanly on top of
> linux-5.10.y. I can send it to <stable@vger.kernel.org> if maintainers
> are okay with the stable-5.10 backport.

If you have a backport, please send it (and cc the original
author/reviewers just to double-check that the backport is correct).

Thanks.

-- 
Catalin