Re: [PATCH v4 03/10] KVM: arm64: Add a range to __pkvm_host_share_guest()

In preparation for supporting stage-2 huge mappings for np-guest. Add a
nr_pages argument to the __pkvm_host_share_guest hypercall. This range
supports only two values: 1 or PMD_SIZE / PAGE_SIZE (that is 512 on a
4K-pages system).

Signed-off-by: Vincent Donnefort <redacted>

diff --git a/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h b/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h
index 26016eb9323f..47aa7b01114f 100644
--- a/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h
+++ b/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h

@@ -39,7 +39,7 @@ int __pkvm_host_donate_hyp(u64 pfn, u64 nr_pages);
 int __pkvm_hyp_donate_host(u64 pfn, u64 nr_pages);
 int __pkvm_host_share_ffa(u64 pfn, u64 nr_pages);
 int __pkvm_host_unshare_ffa(u64 pfn, u64 nr_pages);
-int __pkvm_host_share_guest(u64 pfn, u64 gfn, struct pkvm_hyp_vcpu *vcpu,
+int __pkvm_host_share_guest(u64 pfn, u64 gfn, u64 nr_pages, struct pkvm_hyp_vcpu *vcpu,
 			    enum kvm_pgtable_prot prot);
 int __pkvm_host_unshare_guest(u64 gfn, struct pkvm_hyp_vm *hyp_vm);
 int __pkvm_host_relax_perms_guest(u64 gfn, struct pkvm_hyp_vcpu *vcpu, enum kvm_pgtable_prot prot);

diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
index 59db9606e6e1..4d3d215955c3 100644
--- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c
+++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c

@@ -245,7 +245,8 @@ static void handle___pkvm_host_share_guest(struct kvm_cpu_context *host_ctxt)
 {
 	DECLARE_REG(u64, pfn, host_ctxt, 1);
 	DECLARE_REG(u64, gfn, host_ctxt, 2);
-	DECLARE_REG(enum kvm_pgtable_prot, prot, host_ctxt, 3);
+	DECLARE_REG(u64, nr_pages, host_ctxt, 3);
+	DECLARE_REG(enum kvm_pgtable_prot, prot, host_ctxt, 4);
 	struct pkvm_hyp_vcpu *hyp_vcpu;
 	int ret = -EINVAL;
 

@@ -260,7 +261,7 @@ static void handle___pkvm_host_share_guest(struct kvm_cpu_context *host_ctxt)
 	if (ret)
 		goto out;
 
-	ret = __pkvm_host_share_guest(pfn, gfn, hyp_vcpu, prot);
+	ret = __pkvm_host_share_guest(pfn, gfn, nr_pages, hyp_vcpu, prot);
 out:
 	cpu_reg(host_ctxt, 1) =  ret;
 }

diff --git a/arch/arm64/kvm/hyp/nvhe/mem_protect.c b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
index 4d269210dae0..f0f7c6f83e57 100644
--- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c
+++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c

@@ -696,10 +696,9 @@ static enum pkvm_page_state guest_get_page_state(kvm_pte_t pte, u64 addr)
 	return pkvm_getstate(kvm_pgtable_stage2_pte_prot(pte));
 }
 
-static int __guest_check_page_state_range(struct pkvm_hyp_vcpu *vcpu, u64 addr,
+static int __guest_check_page_state_range(struct pkvm_hyp_vm *vm, u64 addr,
 					  u64 size, enum pkvm_page_state state)
 {
-	struct pkvm_hyp_vm *vm = pkvm_hyp_vcpu_to_hyp_vm(vcpu);
 	struct check_walk_data d = {
 		.desired	= state,
 		.get_page_state	= guest_get_page_state,

@@ -908,48 +907,81 @@ int __pkvm_host_unshare_ffa(u64 pfn, u64 nr_pages)
 	return ret;
 }
 
-int __pkvm_host_share_guest(u64 pfn, u64 gfn, struct pkvm_hyp_vcpu *vcpu,
+static int __guest_check_transition_size(u64 phys, u64 ipa, u64 nr_pages, u64 *size)
+{
+	if (nr_pages == 1) {
+		*size = PAGE_SIZE;
+		return 0;
+	}
+
+	/* We solely support PMD_SIZE huge-pages */
+	if (nr_pages != (1 << (PMD_SHIFT - PAGE_SHIFT)))
+		return -EINVAL;