KVM: arm64: Use kvm_arch in kvm_s2_mmu

In order to make use of the stage 2 pgtable code for the host stage 2,
change kvm_s2_mmu to use a kvm_arch pointer in lieu of the kvm pointer,
as the host will have the former but not the latter.
Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Quentin Perret <qperret@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210319100146.1149909-21-qperret@google.com

arch/arm64/include/asm/kvm_host.h

@@ -94,7 +94,7 @@ struct kvm_s2_mmu {
 	/* The last vcpu id that ran on each physical CPU */
 	int __percpu *last_vcpu_ran;
 
-	struct kvm *kvm;
+	struct kvm_arch *arch;
 };
 
 struct kvm_arch_memory_slot {

arch/arm64/include/asm/kvm_mmu.h

@@ -272,7 +272,7 @@ static __always_inline u64 kvm_get_vttbr(struct kvm_s2_mmu *mmu)
  */
 static __always_inline void __load_guest_stage2(struct kvm_s2_mmu *mmu)
 {
-	write_sysreg(kern_hyp_va(mmu->kvm)->arch.vtcr, vtcr_el2);
+	write_sysreg(kern_hyp_va(mmu->arch)->vtcr, vtcr_el2);
 	write_sysreg(kvm_get_vttbr(mmu), vttbr_el2);
 
 	/*
@@ -283,5 +283,9 @@ static __always_inline void __load_guest_stage2(struct kvm_s2_mmu *mmu)
 	asm(ALTERNATIVE("nop", "isb", ARM64_WORKAROUND_SPECULATIVE_AT));
 }
 
+static inline struct kvm *kvm_s2_mmu_to_kvm(struct kvm_s2_mmu *mmu)
+{
+	return container_of(mmu->arch, struct kvm, arch);
+}
 #endif /* __ASSEMBLY__ */
 #endif /* __ARM64_KVM_MMU_H__ */

arch/arm64/kvm/mmu.c

@@ -165,7 +165,7 @@ static void *kvm_host_va(phys_addr_t phys)
 static void __unmap_stage2_range(struct kvm_s2_mmu *mmu, phys_addr_t start, u64 size,
 				 bool may_block)
 {
-	struct kvm *kvm = mmu->kvm;
+	struct kvm *kvm = kvm_s2_mmu_to_kvm(mmu);
 	phys_addr_t end = start + size;
 
 	assert_spin_locked(&kvm->mmu_lock);
@@ -470,7 +470,7 @@ int kvm_init_stage2_mmu(struct kvm *kvm, struct kvm_s2_mmu *mmu)
 	for_each_possible_cpu(cpu)
 		*per_cpu_ptr(mmu->last_vcpu_ran, cpu) = -1;
 
-	mmu->kvm = kvm;
+	mmu->arch = &kvm->arch;
 	mmu->pgt = pgt;
 	mmu->pgd_phys = __pa(pgt->pgd);
 	mmu->vmid.vmid_gen = 0;
@@ -552,7 +552,7 @@ void stage2_unmap_vm(struct kvm *kvm)
 
 void kvm_free_stage2_pgd(struct kvm_s2_mmu *mmu)
 {
-	struct kvm *kvm = mmu->kvm;
+	struct kvm *kvm = kvm_s2_mmu_to_kvm(mmu);
 	struct kvm_pgtable *pgt = NULL;
 
 	spin_lock(&kvm->mmu_lock);
@@ -621,7 +621,7 @@ int kvm_phys_addr_ioremap(struct kvm *kvm, phys_addr_t guest_ipa,
  */
 static void stage2_wp_range(struct kvm_s2_mmu *mmu, phys_addr_t addr, phys_addr_t end)
 {
-	struct kvm *kvm = mmu->kvm;
+	struct kvm *kvm = kvm_s2_mmu_to_kvm(mmu);
 	stage2_apply_range_resched(kvm, addr, end, kvm_pgtable_stage2_wrprotect);
 }