[PATCH v3 20/32] KVM: arm64: Refactor kvm_arm_setup_stage2()

Quentin Perret
2021-03-03T18:39:00Z

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

No functional change intended.

Signed-off-by: Quentin Perret <qperret@google.com>
---
arch/arm64/include/asm/kvm_pgtable.h | 26 +++++++++++++++++
arch/arm64/kvm/hyp/pgtable.c | 32 +++++++++++++++++++++
arch/arm64/kvm/reset.c | 42 +++-------------------------
3 files changed, 62 insertions(+), 38 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h
index a8255d55c168..21e0985d2e00 100644
--- a/arch/arm64/include/asm/kvm_pgtable.h
+++ b/arch/arm64/include/asm/kvm_pgtable.h
@@ -13,6 +13,16 @@

#define KVM_PGTABLE_MAX_LEVELS 4U

+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;
+}
+
typedef u64 kvm_pte_t;

/**
@@ -159,6 +169,22 @@ void kvm_pgtable_hyp_destroy(struct kvm_pgtable *pgt);
int kvm_pgtable_hyp_map(struct kvm_pgtable *pgt, u64 addr, u64 size, u64 phys,
enum kvm_pgtable_prot prot);

+/**
+ * kvm_get_vtcr() - Helper to construct VTCR_EL2
+ * @mmfr0: Sanitized value of SYS_ID_AA64MMFR0_EL1 register.
+ * @mmfr1: Sanitized value of SYS_ID_AA64MMFR1_EL1 register.
+ * @phys_shfit: Value to set in VTCR_EL2.T0SZ.
+ *
+ * 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.
+ *
+ * Return: VTCR_EL2 value
+ */
+u64 kvm_get_vtcr(u64 mmfr0, u64 mmfr1, u32 phys_shift);
+
/**
* kvm_pgtable_stage2_init() - Initialise a guest stage-2 page-table.
* @pgt: Uninitialised page-table structure to initialise.
diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
index 3d79c8094cdd..296675e5600d 100644
--- a/arch/arm64/kvm/hyp/pgtable.c
+++ b/arch/arm64/kvm/hyp/pgtable.c
@@ -9,6 +9,7 @@

#include <linux/bitfield.h>
#include <asm/kvm_pgtable.h>
+#include <asm/stage2_pgtable.h>

#define KVM_PTE_VALID BIT(0)

@@ -449,6 +450,37 @@ struct stage2_map_data {
struct kvm_pgtable_mm_ops *mm_ops;
};

+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;
+}
+
static int stage2_map_set_prot_attr(enum kvm_pgtable_prot prot,
struct stage2_map_data *data)
{
diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c
index 47f3f035f3ea..6aae118c960a 100644
--- a/arch/arm64/kvm/reset.c
+++ b/arch/arm64/kvm/reset.c
@@ -332,19 +332,10 @@ 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;
@@ -359,33 +350,8 @@ 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;
}