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SubjectRe: [PATCH v3 04/20] kvm: arm64: Clean up VTCR_EL2 initialisation
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Hi Suzuki,

On 06/29/2018 01:15 PM, Suzuki K Poulose wrote:
> Use the new helper for converting the parange to the physical shift.
> Also, add the missing definitions for the VTCR_EL2 register fields
> and use them instead of hard coding numbers.
>
> Cc: Marc Zyngier <marc.zyngier@arm.com>
> Cc: Christoffer Dall <cdall@kernel.org>
> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
> ---
> Changes since V2
> - Part 2 of the split from original patch.
> - Also add missing VTCR field helpers and use them.
> ---
> arch/arm64/include/asm/kvm_arm.h | 3 +++
> arch/arm64/kvm/hyp/s2-setup.c | 30 ++++++------------------------
> 2 files changed, 9 insertions(+), 24 deletions(-)
>
> diff --git a/arch/arm64/include/asm/kvm_arm.h b/arch/arm64/include/asm/kvm_arm.h
> index 6dd285e..3dffd38 100644
> --- a/arch/arm64/include/asm/kvm_arm.h
> +++ b/arch/arm64/include/asm/kvm_arm.h
> @@ -106,6 +106,7 @@
> #define VTCR_EL2_RES1 (1 << 31)
> #define VTCR_EL2_HD (1 << 22)
> #define VTCR_EL2_HA (1 << 21)
> +#define VTCR_EL2_PS_SHIFT TCR_EL2_PS_SHIFT
> #define VTCR_EL2_PS_MASK TCR_EL2_PS_MASK
> #define VTCR_EL2_TG0_MASK TCR_TG0_MASK
> #define VTCR_EL2_TG0_4K TCR_TG0_4K
> @@ -126,6 +127,8 @@
> #define VTCR_EL2_VS_8BIT (0 << VTCR_EL2_VS_SHIFT)
> #define VTCR_EL2_VS_16BIT (1 << VTCR_EL2_VS_SHIFT)
>
> +#define VTCR_EL2_T0SZ(x) TCR_T0SZ(x)
> +
> /*
> * We configure the Stage-2 page tables to always restrict the IPA space to be
> * 40 bits wide (T0SZ = 24). Systems with a PARange smaller than 40 bits are
> diff --git a/arch/arm64/kvm/hyp/s2-setup.c b/arch/arm64/kvm/hyp/s2-setup.c
> index 603e1ee..81094f1 100644
> --- a/arch/arm64/kvm/hyp/s2-setup.c
> +++ b/arch/arm64/kvm/hyp/s2-setup.c
> @@ -19,11 +19,13 @@
> #include <asm/kvm_arm.h>
> #include <asm/kvm_asm.h>
> #include <asm/kvm_hyp.h>
> +#include <asm/cpufeature.h>
>
> u32 __hyp_text __init_stage2_translation(void)
> {
> u64 val = VTCR_EL2_FLAGS;
> u64 parange;
> + u32 phys_shift;
> u64 tmp;

Not related to this patch but the comment reporting that bit 19 of
VTCR_EL2 is RES0 is not fully valid anymore as it now corresponds to
VMID size in ARM ARM >= 8.1.
>
> /*
> @@ -34,30 +36,10 @@ u32 __hyp_text __init_stage2_translation(void)
> parange = read_sysreg(id_aa64mmfr0_el1) & 7;
> if (parange > ID_AA64MMFR0_PARANGE_MAX)
> parange = ID_AA64MMFR0_PARANGE_MAX;
> - val |= parange << 16;
> + val |= parange << VTCR_EL2_PS_SHIFT;
>
> /* Compute the actual PARange... */
> - switch (parange) {
> - case 0:
> - parange = 32;
> - break;
> - case 1:
> - parange = 36;
> - break;
> - case 2:
> - parange = 40;
> - break;
> - case 3:
> - parange = 42;
> - break;
> - case 4:
> - parange = 44;
> - break;
> - case 5:
> - default:
> - parange = 48;
> - break;
> - }
> + phys_shift = id_aa64mmfr0_parange_to_phys_shift(parange);
>
> /*
> * ... and clamp it to 40 bits, unless we have some braindead
> @@ -65,7 +47,7 @@ u32 __hyp_text __init_stage2_translation(void)
> * return that value for the rest of the kernel to decide what
> * to do.
> */
> - val |= 64 - (parange > 40 ? 40 : parange);
> + val |= VTCR_EL2_T0SZ(phys_shift > 40 ? 40 : phys_shift);
>
> /*
> * Check the availability of Hardware Access Flag / Dirty Bit
> @@ -86,5 +68,5 @@ u32 __hyp_text __init_stage2_translation(void)
>
> write_sysreg(val, vtcr_el2);
>
> - return parange;
> + return phys_shift;
Reviewed-by: Eric Auger <eric.auger@redhat.com>

Thanks

Eric

> }
>

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