[PATCH v1 14/16] kvm: arm64: Switch to per VM IPA

[Suzuki K Poulose]

Now that we can manage the stage2 page table per VM, switch the
configuration details to per VM instance. We keep track of the
IPA bits, number of page table levels and the VTCR bits (which
depends on the IPA and the number of levels).

Cc: Marc Zyngier <marc.zyngier@xxxxxxx>
Cc: Christoffer Dall <cdall@xxxxxxxxxx>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
---
 arch/arm/include/asm/kvm_mmu.h          |  1 +
 arch/arm64/include/asm/kvm_host.h       | 12 ++++++++++++
 arch/arm64/include/asm/kvm_mmu.h        | 22 ++++++++++++++++++++--
 arch/arm64/include/asm/stage2_pgtable.h |  1 -
 arch/arm64/kvm/hyp/switch.c             |  3 +--
 virt/kvm/arm/arm.c                      |  2 +-
 6 files changed, 35 insertions(+), 6 deletions(-)

diff --git a/arch/arm/include/asm/kvm_mmu.h b/arch/arm/include/asm/kvm_mmu.h
index 440c80589453..dd592fe45660 100644
--- a/arch/arm/include/asm/kvm_mmu.h
+++ b/arch/arm/include/asm/kvm_mmu.h
@@ -48,6 +48,7 @@
 #define kvm_vttbr_baddr_mask(kvm)	VTTBR_BADDR_MASK
 
 #define stage2_pgd_size(kvm)	(PTRS_PER_S2_PGD * sizeof(pgd_t))
+#define kvm_init_stage2_config(kvm)	do { } while (0)
 int create_hyp_mappings(void *from, void *to, pgprot_t prot);
 int create_hyp_io_mappings(void *from, void *to, phys_addr_t);
 void free_hyp_pgds(void);
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 9a9ddeb33c84..1e66e5ab3dde 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -64,6 +64,18 @@ struct kvm_arch {
 	/* VTTBR value associated with above pgd and vmid */
 	u64    vttbr;
 
+	/* Private bits of VTCR_EL2 for this VM */
+	u64    vtcr_private;
+	/* Size of the PA size for this guest */
+	u8     phys_shift;
+	/*
+	 * Number of levels in page table. We could always calculate
+	 * it from phys_shift above. We cache it for faster switches
+	 * in stage2 page table helpers.
+	 */
+	u8     s2_levels;
+
+
 	/* The last vcpu id that ran on each physical CPU */
 	int __percpu *last_vcpu_ran;
 
diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h
index 483185ed2ecd..ab6a8b905065 100644
--- a/arch/arm64/include/asm/kvm_mmu.h
+++ b/arch/arm64/include/asm/kvm_mmu.h
@@ -134,11 +134,12 @@ static inline unsigned long __kern_hyp_va(unsigned long v)
 /*
  * We currently only support a 40bit IPA.
  */
-#define KVM_PHYS_SHIFT	(40)
+#define KVM_PHYS_SHIFT_DEFAULT	(40)
 
-#define kvm_phys_shift(kvm)		KVM_PHYS_SHIFT
+#define kvm_phys_shift(kvm)		(kvm->arch.phys_shift)
 #define kvm_phys_size(kvm)		(_AC(1, ULL) << kvm_phys_shift(kvm))
 #define kvm_phys_mask(kvm)		(kvm_phys_size(kvm) - _AC(1, ULL))
+#define kvm_stage2_levels(kvm)		(kvm->arch.s2_levels)
 
 static inline bool kvm_page_empty(void *ptr)
 {
@@ -346,5 +347,22 @@ static inline u64 kvm_vttbr_baddr_mask(struct kvm *kvm)
 	return GENMASK_ULL(PHYS_MASK_SHIFT - 1, x);
 }
 
+/*
+ * kvm_init_stage2_config: Initialise the VM specific stage2 page table
+ * details to default IPA size.
+ */
+static inline void kvm_init_stage2_config(struct kvm *kvm)
+{
+	/*
+	 * The stage2 PGD is dependent on the settings we initialise here
+	 * and should be allocated only after this step.
+	 */
+	VM_BUG_ON(kvm->arch.pgd != NULL);
+	kvm->arch.phys_shift = KVM_PHYS_SHIFT_DEFAULT;
+	kvm->arch.s2_levels = stage2_pt_levels(kvm->arch.phys_shift);
+	kvm->arch.vtcr_private = VTCR_EL2_SL0(kvm->arch.s2_levels) |
+				 TCR_T0SZ(kvm->arch.phys_shift);
+}
+
 #endif /* __ASSEMBLY__ */
 #endif /* __ARM64_KVM_MMU_H__ */
diff --git a/arch/arm64/include/asm/stage2_pgtable.h b/arch/arm64/include/asm/stage2_pgtable.h
index 33e8ebb25037..9b75b83da643 100644
--- a/arch/arm64/include/asm/stage2_pgtable.h
+++ b/arch/arm64/include/asm/stage2_pgtable.h
@@ -44,7 +44,6 @@
  */
 #define __s2_pgd_ptrs(pa, lvls)	(1 << ((pa) - pt_levels_pgdir_shift((lvls))))
 
-#define kvm_stage2_levels(kvm)		stage2_pt_levels(kvm_phys_shift(kvm))
 #define stage2_pgdir_shift(kvm)	\
 		pt_levels_pgdir_shift(kvm_stage2_levels(kvm))
 #define stage2_pgdir_size(kvm)		(_AC(1, UL) << stage2_pgdir_shift((kvm)))
diff --git a/arch/arm64/kvm/hyp/switch.c b/arch/arm64/kvm/hyp/switch.c
index 523471f0af7b..d0725562ee3f 100644
--- a/arch/arm64/kvm/hyp/switch.c
+++ b/arch/arm64/kvm/hyp/switch.c
@@ -160,8 +160,7 @@ static void __hyp_text __activate_vm(struct kvm_vcpu *vcpu)
 	u64 vtcr = read_sysreg(vtcr_el2);
 
 	vtcr &= ~VTCR_EL2_PRIVATE_MASK;
-	vtcr |= VTCR_EL2_SL0(stage2_pt_levels(kvm)) |
-		VTCR_EL2_T0SZ(kvm_phys_shift(kvm));
+	vtcr |= kvm->arch.vtcr_private;
 	write_sysreg(vtcr, vtcr_el2);
 	write_sysreg(kvm->arch.vttbr, vttbr_el2);
 }
diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c
index 8564ed907b18..e0bf8d19fcfe 100644
--- a/virt/kvm/arm/arm.c
+++ b/virt/kvm/arm/arm.c
@@ -143,7 +143,7 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
 	/* The maximum number of VCPUs is limited by the host's GIC model */
 	kvm->arch.max_vcpus = vgic_present ?
 				kvm_vgic_get_max_vcpus() : KVM_MAX_VCPUS;
-
+	kvm_init_stage2_config(kvm);
 	return ret;
 }
 
-- 
2.13.6