Re: [PATCH] arm64/mm: Fix __enable_mmu() for new TGRAN range values
From: Anshuman Khandual <hidden>
Date: 2021-03-07 11:54:58
Also in:
kvmarm, linux-efi, lkml
On 3/5/21 8:21 PM, Mark Rutland wrote:
On Fri, Mar 05, 2021 at 08:06:09PM +0530, Anshuman Khandual wrote:quoted
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 Signed-off-by: James Morse <james.morse@arm.com> Signed-off-by: Anshuman Khandual <redacted> --- arch/arm64/include/asm/sysreg.h | 20 ++++++++++++++------ arch/arm64/kernel/head.S | 6 ++++-- arch/arm64/kvm/reset.c | 23 ++++++++++++----------- drivers/firmware/efi/libstub/arm64-stub.c | 2 +- 4 files changed, 31 insertions(+), 20 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 0x7The TGRAN2 fields doesn't quite follow the usual ID scheme rules, so how do we deteremine the max value? Does the ARM ARM say anything in particular about them, like we do for some of the PMU ID fields?
Did not find anything in ARM ARM, regarding what scheme TGRAN2 fields actually follow. I had arrived at more restrictive 0x7 value, like the usual signed fields as the TGRAN4 fields definitely do not follow the unsigned ID scheme. Would restricting max value to 0x3 (i.e LPA2) be a better option instead ?
Otherwise, this patch looks correct to me. Thanks, Mark.
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