From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Suzuki K. Poulose" Subject: Re: [PATCH 12/14] arm64: Check for selected granule support Date: Thu, 13 Aug 2015 15:45:07 +0100 Message-ID: <55CCAD73.7080702@arm.com> References: <1439465645-22584-1-git-send-email-suzuki.poulose@arm.com> <1439465645-22584-13-git-send-email-suzuki.poulose@arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Cc: "kvm@vger.kernel.org" , Marc Zyngier , Catalin Marinas , Will Deacon , "linux-kernel@vger.kernel.org" , "kvmarm@lists.cs.columbia.edu" , "linux-arm-kernel@lists.infradead.org" To: Steve Capper Return-path: In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu List-Id: kvm.vger.kernel.org On 13/08/15 13:28, Steve Capper wrote: > On 13 August 2015 at 12:34, Suzuki K. Poulose wrote: >> From: "Suzuki K. Poulose" >> >> Ensure that the selected page size is supported by the >> CPU(s). >> >> Cc: Mark Rutland >> Cc: Catalin Marinas >> Cc: Will Deacon >> Signed-off-by: Suzuki K. Poulose >> --- >> 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 >> #include >> #include >> -#include >> #include >> #include >> #include >> +#include >> +#include >> #include >> >> #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 >