On 08/02/18 11:00, Christoffer Dall wrote:
On Tue, Jan 09, 2018 at 07:04:00PM +0000, Suzuki K Poulose wrote:
Add a helper to convert ID_AA64MMFR0_EL1:PARange to they physical
                                                       *the*
size shift. Limit the size to the maximum supported by the kernel.


Is this just a cleanup or are we actually going to need this feature in
the subsequent patches?  That would be nice to motivate in the commit
letter.

It is a cleanup, plus we are going to move the user of the code around from
one place to the other. So this makes it a bit easier and cleaner.



Cc: Mark Rutland <mark.rutl...@arm.com>
Cc: Catalin Marinas <catalin.mari...@arm.com>
Cc: Will Deacon <will.dea...@arm.com>
Cc: Marc Zyngier <marc.zyng...@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poul...@arm.com>
---
  arch/arm64/include/asm/cpufeature.h | 16 ++++++++++++++++
  arch/arm64/kvm/hyp/s2-setup.c       | 28 +++++-----------------------
  2 files changed, 21 insertions(+), 23 deletions(-)

diff --git a/arch/arm64/include/asm/cpufeature.h 
b/arch/arm64/include/asm/cpufeature.h
index ac67cfc2585a..0564e14616eb 100644
--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -304,6 +304,22 @@ static inline u64 read_zcr_features(void)
        return zcr;
  }
+static inline u32 id_aa64mmfr0_parange_to_phys_shift(int parange)
+{
+       switch (parange) {
+       case 0: return 32;
+       case 1: return 36;
+       case 2: return 40;
+       case 3: return 42;
+       case 4: return 44;
+
+       default:

What is the case we want to cater for with making parange == 5 the
default for unrecognized values?

(I have a feeling that default label comes from making the compiler
happy about potentially uninitialized values once upon a time before a
lot of refactoring happened here.)

That is there to make sure we return 48 iff 52bit support (for that matter,
if there is a new limit in the future) is not enabled.


+       case 5: return 48;
+#ifdef CONFIG_ARM64_PA_BITS_52
+       case 6: return 52;
+#endif
+       }
+}
  #endif /* __ASSEMBLY__ */




Could you fold this change into the commit as well:

diff --git a/arch/arm64/kvm/hyp/s2-setup.c b/arch/arm64/kvm/hyp/s2-setup.c
index 603e1ee83e89..eea2fbd68b8a 100644
--- a/arch/arm64/kvm/hyp/s2-setup.c
+++ b/arch/arm64/kvm/hyp/s2-setup.c
@@ -29,7 +29,8 @@ u32 __hyp_text __init_stage2_translation(void)
        /*
         * Read the PARange bits from ID_AA64MMFR0_EL1 and set the PS
         * bits in VTCR_EL2. Amusingly, the PARange is 4 bits, while
-        * PS is only 3. Fortunately, bit 19 is RES0 in VTCR_EL2...
+        * PS is only 3. Fortunately, only three bits is actually used to
+        * enode the supported PARange values.
         */
        parange = read_sysreg(id_aa64mmfr0_el1) & 7;
        if (parange > ID_AA64MMFR0_PARANGE_MAX)

Sure.

Thanks for the review.

Suzuki

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