Messages in this thread | | | Subject | Re: [RFC 07/10] arm64/mm: Detect and enable FEAT_LPA2 | From | Suzuki K Poulose <> | Date | Wed, 14 Jul 2021 09:21:00 +0100 |
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On 14/07/2021 03:21, Anshuman Khandual wrote: > Detect FEAT_LPA2 implementation early enough during boot when requested via > CONFIG_ARM64_PA_BITS_52_LPA2 and remember in a variable arm64_lpa2_enabled. > This variable could then be used to turn on TCR_EL1.TCR_DS effecting the 52 > bits PA range or fall back to default 48 bits PA range if FEAT_LPA2 feature > was requested but found not to be implemented. > > Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com> > --- > arch/arm64/include/asm/memory.h | 1 + > arch/arm64/kernel/head.S | 15 +++++++++++++++ > arch/arm64/mm/mmu.c | 3 +++ > arch/arm64/mm/proc.S | 9 +++++++++ > 4 files changed, 28 insertions(+) > > diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h > index 824a365..d0ca002 100644 > --- a/arch/arm64/include/asm/memory.h > +++ b/arch/arm64/include/asm/memory.h > @@ -178,6 +178,7 @@ > #include <asm/bug.h> > > extern u64 vabits_actual; > +extern u64 arm64_lpa2_enabled; > > extern s64 memstart_addr; > /* PHYS_OFFSET - the physical address of the start of memory. */ > diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S > index 6444147..9cf79ea 100644 > --- a/arch/arm64/kernel/head.S > +++ b/arch/arm64/kernel/head.S > @@ -94,6 +94,21 @@ SYM_CODE_START(primary_entry) > adrp x23, __PHYS_OFFSET > and x23, x23, MIN_KIMG_ALIGN - 1 // KASLR offset, defaults to 0 > bl set_cpu_boot_mode_flag > + > +#ifdef CONFIG_ARM64_PA_BITS_52_LPA2 > + mrs x10, ID_AA64MMFR0_EL1 > + ubfx x10, x10, #ID_AA64MMFR0_TGRAN_SHIFT, 4 > + cmp x10, #ID_AA64MMFR0_TGRAN_LPA2 > + b.ne 1f
For the sake of forward compatibility, this should be "b.lt"
Suzuki
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