[RFC PATCH 21/27] KVM: arm64: Refactor kvm_arm_setup_stage2()

From: Quentin Perret
Date: Tue Nov 17 2020 - 13:17:18 EST


In order to re-use some of the stage 2 setup at EL2, factor parts of
kvm_arm_setup_stage2() out into static inline functions.

No functional change intended.

Signed-off-by: Quentin Perret <qperret@xxxxxxxxxx>
---
arch/arm64/include/asm/kvm_mmu.h | 48 ++++++++++++++++++++++++++++++++
arch/arm64/kvm/reset.c | 42 +++-------------------------
2 files changed, 52 insertions(+), 38 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h
index 714357ebd278..5a76358e8c7a 100644
--- a/arch/arm64/include/asm/kvm_mmu.h
+++ b/arch/arm64/include/asm/kvm_mmu.h
@@ -256,6 +256,54 @@ static inline int kvm_write_guest_lock(struct kvm *kvm, gpa_t gpa,
return ret;
}

+static inline u64 kvm_get_parange(u64 mmfr0)
+{
+ u64 parange = cpuid_feature_extract_unsigned_field(mmfr0,
+ ID_AA64MMFR0_PARANGE_SHIFT);
+ if (parange > ID_AA64MMFR0_PARANGE_MAX)
+ parange = ID_AA64MMFR0_PARANGE_MAX;
+
+ return parange;
+}
+
+/*
+ * The VTCR value is common across all the physical CPUs on the system.
+ * We use system wide sanitised values to fill in different fields,
+ * except for Hardware Management of Access Flags. HA Flag is set
+ * unconditionally on all CPUs, as it is safe to run with or without
+ * the feature and the bit is RES0 on CPUs that don't support it.
+ */
+static inline u64 kvm_get_vtcr(u64 mmfr0, u64 mmfr1, u32 phys_shift)
+{
+ u64 vtcr = VTCR_EL2_FLAGS;
+ u8 lvls;
+
+ vtcr |= kvm_get_parange(mmfr0) << VTCR_EL2_PS_SHIFT;
+ vtcr |= VTCR_EL2_T0SZ(phys_shift);
+ /*
+ * Use a minimum 2 level page table to prevent splitting
+ * host PMD huge pages at stage2.
+ */
+ lvls = stage2_pgtable_levels(phys_shift);
+ if (lvls < 2)
+ lvls = 2;
+ vtcr |= VTCR_EL2_LVLS_TO_SL0(lvls);
+
+ /*
+ * Enable the Hardware Access Flag management, unconditionally
+ * on all CPUs. The features is RES0 on CPUs without the support
+ * and must be ignored by the CPUs.
+ */
+ vtcr |= VTCR_EL2_HA;
+
+ /* Set the vmid bits */
+ vtcr |= (get_vmid_bits(mmfr1) == 16) ?
+ VTCR_EL2_VS_16BIT :
+ VTCR_EL2_VS_8BIT;
+
+ return vtcr;
+}
+
#define kvm_phys_to_vttbr(addr) phys_to_ttbr(addr)

static __always_inline u64 kvm_get_vttbr(struct kvm_s2_mmu *mmu)
diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c
index 3e772ea4e066..074b39dbe539 100644
--- a/arch/arm64/kvm/reset.c
+++ b/arch/arm64/kvm/reset.c
@@ -384,19 +384,10 @@ int kvm_set_ipa_limit(void)
return 0;
}

-/*
- * Configure the VTCR_EL2 for this VM. The VTCR value is common
- * across all the physical CPUs on the system. We use system wide
- * sanitised values to fill in different fields, except for Hardware
- * Management of Access Flags. HA Flag is set unconditionally on
- * all CPUs, as it is safe to run with or without the feature and
- * the bit is RES0 on CPUs that don't support it.
- */
int kvm_arm_setup_stage2(struct kvm *kvm, unsigned long type)
{
- u64 vtcr = VTCR_EL2_FLAGS, mmfr0;
- u32 parange, phys_shift;
- u8 lvls;
+ u64 mmfr0, mmfr1;
+ u32 phys_shift;

if (type & ~KVM_VM_TYPE_ARM_IPA_SIZE_MASK)
return -EINVAL;
@@ -411,33 +402,8 @@ int kvm_arm_setup_stage2(struct kvm *kvm, unsigned long type)
}

mmfr0 = read_sanitised_ftr_reg(SYS_ID_AA64MMFR0_EL1);
- parange = cpuid_feature_extract_unsigned_field(mmfr0,
- ID_AA64MMFR0_PARANGE_SHIFT);
- if (parange > ID_AA64MMFR0_PARANGE_MAX)
- parange = ID_AA64MMFR0_PARANGE_MAX;
- vtcr |= parange << VTCR_EL2_PS_SHIFT;
-
- vtcr |= VTCR_EL2_T0SZ(phys_shift);
- /*
- * Use a minimum 2 level page table to prevent splitting
- * host PMD huge pages at stage2.
- */
- lvls = stage2_pgtable_levels(phys_shift);
- if (lvls < 2)
- lvls = 2;
- vtcr |= VTCR_EL2_LVLS_TO_SL0(lvls);
-
- /*
- * Enable the Hardware Access Flag management, unconditionally
- * on all CPUs. The features is RES0 on CPUs without the support
- * and must be ignored by the CPUs.
- */
- vtcr |= VTCR_EL2_HA;
+ mmfr1 = read_sanitised_ftr_reg(SYS_ID_AA64MMFR1_EL1);
+ kvm->arch.vtcr = kvm_get_vtcr(mmfr0, mmfr1, phys_shift);

- /* Set the vmid bits */
- vtcr |= (kvm_get_vmid_bits() == 16) ?
- VTCR_EL2_VS_16BIT :
- VTCR_EL2_VS_8BIT;
- kvm->arch.vtcr = vtcr;
return 0;
}
--
2.29.2.299.gdc1121823c-goog