From: "Suzuki K. Poulose" <Suzuki.Poulose@arm.com>
To: Steve Capper <steve.capper@linaro.org>
Cc: "linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
Marc Zyngier <Marc.Zyngier@arm.com>,
Catalin Marinas <Catalin.Marinas@arm.com>,
Will Deacon <Will.Deacon@arm.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"kvmarm@lists.cs.columbia.edu" <kvmarm@lists.cs.columbia.edu>
Subject: Re: [PATCH 12/14] arm64: Check for selected granule support
Date: Thu, 13 Aug 2015 15:45:07 +0100 [thread overview]
Message-ID: <55CCAD73.7080702@arm.com> (raw)
In-Reply-To: <CAPvkgC3=S1BxdzZM4uUOmyXLjii48SMpCof6i6HdNeTG_fydfg@mail.gmail.com>
On 13/08/15 13:28, Steve Capper wrote:
> On 13 August 2015 at 12:34, Suzuki K. Poulose <suzuki.poulose@arm.com> wrote:
>> From: "Suzuki K. Poulose" <suzuki.poulose@arm.com>
>>
>> Ensure that the selected page size is supported by the
>> CPU(s).
>>
>> Cc: Mark Rutland <mark.rutland@arm.com>
>> Cc: Catalin Marinas <catalin.marinas@arm.com>
>> Cc: Will Deacon <will.deacon@arm.com>
>> Signed-off-by: Suzuki K. Poulose <suzuki.poulose@arm.com>
>> ---
>> arch/arm64/include/asm/sysreg.h | 6 ++++++
>> arch/arm64/kernel/head.S | 24 +++++++++++++++++++++++-
>> 2 files changed, 29 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h
>> index a7f3d4b..e01d323 100644
>> --- a/arch/arm64/include/asm/sysreg.h
>> +++ b/arch/arm64/include/asm/sysreg.h
>> @@ -87,4 +87,10 @@ static inline void config_sctlr_el1(u32 clear, u32 set)
>> }
>> #endif
>>
>> +#define ID_AA64MMFR0_TGran4_SHIFT 28
>> +#define ID_AA64MMFR0_TGran64_SHIFT 24
>> +
>> +#define ID_AA64MMFR0_TGran4_ENABLED 0x0
>> +#define ID_AA64MMFR0_TGran64_ENABLED 0x0
>> +
>> #endif /* __ASM_SYSREG_H */
>> diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
>> index 01b8e58..0cb04db 100644
>> --- a/arch/arm64/kernel/head.S
>> +++ b/arch/arm64/kernel/head.S
>> @@ -31,10 +31,11 @@
>> #include <asm/cputype.h>
>> #include <asm/kernel-pgtable.h>
>> #include <asm/memory.h>
>> -#include <asm/thread_info.h>
>> #include <asm/pgtable-hwdef.h>
>> #include <asm/pgtable.h>
>> #include <asm/page.h>
>> +#include <asm/sysreg.h>
>> +#include <asm/thread_info.h>
>> #include <asm/virt.h>
>>
>> #define __PHYS_OFFSET (KERNEL_START - TEXT_OFFSET)
>> @@ -606,9 +607,25 @@ ENDPROC(__secondary_switched)
>> * x27 = *virtual* address to jump to upon completion
>> *
>> * other registers depend on the function called upon completion
>> + * Checks if the selected granule size is supported by the CPU.
>> */
>> +#if defined(CONFIG_ARM64_64K_PAGES)
>> +
>> +#define ID_AA64MMFR0_TGran_SHIFT ID_AA64MMFR0_TGran64_SHIFT
>> +#define ID_AA64MMFR0_TGran_ENABLED ID_AA64MMFR0_TGran64_ENABLED
>> +
>> +#else
>> +
>> +#define ID_AA64MMFR0_TGran_SHIFT ID_AA64MMFR0_TGran4_SHIFT
>> +#define ID_AA64MMFR0_TGran_ENABLED ID_AA64MMFR0_TGran4_ENABLED
>> +
>> +#endif
>> .section ".idmap.text", "ax"
>> __enable_mmu:
>> + mrs x1, ID_AA64MMFR0_EL1
>> + ubfx x2, x1, #ID_AA64MMFR0_TGran_SHIFT, 4
>> + cmp x2, #ID_AA64MMFR0_TGran_ENABLED
>> + b.ne __no_granule_support
>> ldr x5, =vectors
>> msr vbar_el1, x5
>> msr ttbr0_el1, x25 // load TTBR0
>> @@ -626,3 +643,8 @@ __enable_mmu:
>> isb
>> br x27
>> ENDPROC(__enable_mmu)
>> +
>> +__no_granule_support:
>> + wfe
>> + b __no_granule_support
>> +ENDPROC(__no_granule_support)
>> --
>> 1.7.9.5
>>
>
> Hi Suzuki,
> Is is possible to tell the user that the kernel has failed to boot due
> to the kernel granule being unsupported?
We don't have anything up at this time. The "looping address" is actually a clue
to the (expert) user. Not sure we can do something, until we get something like DEBUG_LL(?)
Or we should let it continue and end in a panic(?). The current situation can boot a
multi-cluster system with boot cluster having the Tgran support(which doesn't make a
strong use case though). I will try out some options and get back to you.
Thanks
Suzuki
>
> Cheers,
> --
> Steve
>
next prev parent reply other threads:[~2015-08-13 14:45 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-08-13 11:33 [PATCH 00/14] arm64: 16K translation granule support Suzuki K. Poulose
2015-08-13 11:33 ` [PATCH 01/14] arm64: Move swapper pagetable definitions Suzuki K. Poulose
2015-08-13 11:33 ` [PATCH 02/14] arm64: Handle section maps for swapper/idmap Suzuki K. Poulose
2015-09-02 9:38 ` Ard Biesheuvel
2015-09-02 9:42 ` Suzuki K. Poulose
2015-09-02 10:00 ` Ard Biesheuvel
2015-08-13 11:33 ` [PATCH 03/14] arm64: Introduce helpers for page table levels Suzuki K. Poulose
2015-08-13 11:33 ` [PATCH 04/14] arm64: Calculate size for idmap_pg_dir at compile time Suzuki K. Poulose
2015-08-13 11:33 ` [PATCH 05/14] arm64: Handle 4 level page table for swapper Suzuki K. Poulose
2015-08-13 11:33 ` [PATCH 06/14] arm64: Clean config usages for page size Suzuki K. Poulose
2015-08-13 11:33 ` [PATCH 07/14] arm64: Kconfig: Fix help text about AArch32 support with 64K pages Suzuki K. Poulose
2015-08-13 11:33 ` [PATCH 08/14] arm64: kvm: Fix {V}TCR_EL2_TG0 mask Suzuki K. Poulose
2015-08-13 11:33 ` [PATCH 09/14] arm64: Cleanup VTCR_EL2 computation Suzuki K. Poulose
2015-08-13 11:34 ` [PATCH 10/14] arm: kvm: Move fake PGD handling to arch specific files Suzuki K. Poulose
2015-08-13 11:34 ` [PATCH 11/14] arm64: kvm: Rewrite fake pgd handling Suzuki K. Poulose
2015-08-13 11:34 ` [PATCH 12/14] arm64: Check for selected granule support Suzuki K. Poulose
2015-08-13 12:28 ` Steve Capper
2015-08-13 14:45 ` Suzuki K. Poulose [this message]
2015-08-13 17:29 ` Catalin Marinas
2015-09-02 9:48 ` Ard Biesheuvel
2015-09-02 10:19 ` Ard Biesheuvel
2015-09-04 13:58 ` Catalin Marinas
2015-08-13 11:34 ` [PATCH 13/14] arm64: Add 16K page size support Suzuki K. Poulose
2015-08-13 11:34 ` [PATCH 14/14] arm64: 36 bit VA Suzuki K. Poulose
2015-09-02 9:55 ` [PATCH 00/14] arm64: 16K translation granule support Ard Biesheuvel
2015-09-02 10:11 ` Suzuki K. Poulose
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