[PATCH 09/20] KVM: arm64: Add a range to __pkvm_guest_share_host()

[Vincent Donnefort]

In preparation for supporting stage-2 huge mappings for protected VMs, add a
nr_pages argument to the __pkvm_guest_share_host() 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 <vdonnefort at google.com>

diff --git a/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h b/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h
index 678bb55c694a..7fdfe3f22c5a 100644
--- a/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h
+++ b/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h
@@ -32,7 +32,7 @@ enum pkvm_component_id {
 
 int __pkvm_prot_finalize(void);
 int __pkvm_host_share_hyp(u64 pfn, u64 nr_pages);
-int __pkvm_guest_share_host(struct pkvm_hyp_vcpu *vcpu, u64 gfn);
+int __pkvm_guest_share_host(struct pkvm_hyp_vcpu *vcpu, u64 gfn, u64 nr_pages);
 int __pkvm_guest_unshare_host(struct pkvm_hyp_vcpu *vcpu, u64 gfn);
 int __pkvm_host_unshare_hyp(u64 pfn, u64 nr_pages);
 int __pkvm_host_donate_hyp(u64 pfn, u64 nr_pages);
diff --git a/arch/arm64/kvm/hyp/nvhe/mem_protect.c b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
index ce637f1a55b3..53c48cea5f0e 100644
--- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c
+++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
@@ -1004,31 +1004,37 @@ int __pkvm_host_share_hyp(u64 pfn, u64 nr_pages)
 	return ret;
 }
 
-int __pkvm_guest_share_host(struct pkvm_hyp_vcpu *vcpu, u64 gfn)
+static int __guest_check_transition_size(u64 phys, u64 ipa, u64 nr_pages, u64 *size);
+
+int __pkvm_guest_share_host(struct pkvm_hyp_vcpu *vcpu, u64 gfn, u64 nr_pages)
 {
 	struct pkvm_hyp_vm *vm = pkvm_hyp_vcpu_to_hyp_vm(vcpu);
-	u64 phys, ipa = hyp_pfn_to_phys(gfn);
+	u64 size, phys, ipa = hyp_pfn_to_phys(gfn);
 	kvm_pte_t pte;
 	int ret;
 
+	ret = __guest_check_transition_size(0, ipa, nr_pages, &size);
+	if (ret)
+		return ret;
+
 	host_lock_component();
 	guest_lock_component(vm);
 
-	ret = get_valid_guest_pte(vm, ipa, PAGE_SIZE, &pte, &phys);
+	ret = get_valid_guest_pte(vm, ipa, size, &pte, &phys);
 	if (ret)
 		goto unlock;
 
 	ret = -EPERM;
 	if (pkvm_getstate(kvm_pgtable_stage2_pte_prot(pte)) != PKVM_PAGE_OWNED)
 		goto unlock;
-	if (__host_check_page_state_range(phys, PAGE_SIZE, PKVM_NOPAGE))
+	if (__host_check_page_state_range(phys, size, PKVM_NOPAGE))
 		goto unlock;
 
 	ret = 0;
-	WARN_ON(kvm_pgtable_stage2_map(&vm->pgt, ipa, PAGE_SIZE, phys,
+	WARN_ON(kvm_pgtable_stage2_map(&vm->pgt, ipa, size, phys,
 				       pkvm_mkstate(KVM_PGTABLE_PROT_RWX, PKVM_PAGE_SHARED_OWNED),
 				       &vcpu->vcpu.arch.pkvm_memcache, 0));
-	WARN_ON(__host_set_page_state_range(phys, PAGE_SIZE, PKVM_PAGE_SHARED_BORROWED));
+	WARN_ON(__host_set_page_state_range(phys, size, PKVM_PAGE_SHARED_BORROWED));
 unlock:
 	guest_unlock_component(vm);
 	host_unlock_component();
@@ -1917,8 +1923,8 @@ int __pkvm_ownership_selftest(u64 pfn, u64 pgtable_pfn, unsigned long pgtable_nr
 
 	selftest_state.host = PKVM_PAGE_SHARED_BORROWED;
 	selftest_state.guest[0] = PKVM_PAGE_SHARED_OWNED;
-	assert_transition_res(0,	__pkvm_guest_share_host, vcpu, gfn);
-	assert_transition_res(-EPERM,	__pkvm_guest_share_host, vcpu, gfn);
+	assert_transition_res(0,	__pkvm_guest_share_host, vcpu, gfn, 1);
+	assert_transition_res(-EPERM,	__pkvm_guest_share_host, vcpu, gfn, 1);
 	assert_transition_res(-EPERM,	__pkvm_host_donate_guest, pfn, gfn, 1, vcpu);
 	assert_transition_res(-EPERM,	__pkvm_host_donate_guest, pfn, gfn + 1, 1, vcpu);
 	assert_transition_res(-EPERM,	__pkvm_host_share_guest, pfn, gfn, 1, vcpu, prot);
@@ -1948,7 +1954,7 @@ int __pkvm_ownership_selftest(u64 pfn, u64 pgtable_pfn, unsigned long pgtable_nr
 	assert_transition_res(0,	__pkvm_host_force_reclaim_page_guest, phys);
 	assert_transition_res(-EPERM,	__pkvm_host_donate_guest, pfn, gfn, 1, vcpu);
 	assert_transition_res(-EPERM,	__pkvm_host_share_guest, pfn, gfn, 1, vcpu, prot);
-	assert_transition_res(-EHWPOISON, __pkvm_guest_share_host, vcpu, gfn);
+	assert_transition_res(-EHWPOISON, __pkvm_guest_share_host, vcpu, gfn, 1);
 	assert_transition_res(-EHWPOISON, __pkvm_guest_unshare_host, vcpu, gfn);
 
 	selftest_state.host = PKVM_NOPAGE;
diff --git a/arch/arm64/kvm/hyp/nvhe/pkvm.c b/arch/arm64/kvm/hyp/nvhe/pkvm.c
index 8f5d32cdb4eb..f8e2618c78e3 100644
--- a/arch/arm64/kvm/hyp/nvhe/pkvm.c
+++ b/arch/arm64/kvm/hyp/nvhe/pkvm.c
@@ -1091,7 +1091,7 @@ static bool pkvm_memshare_call(u64 *ret, struct kvm_vcpu *vcpu, u64 *exit_code)
 		goto out_guest;
 
 	hyp_vcpu = container_of(vcpu, struct pkvm_hyp_vcpu, vcpu);
-	switch (__pkvm_guest_share_host(hyp_vcpu, hyp_phys_to_pfn(ipa))) {
+	switch (__pkvm_guest_share_host(hyp_vcpu, hyp_phys_to_pfn(ipa), 1)) {
 	case 0:
 		ret[0] = SMCCC_RET_SUCCESS;
 		goto out_guest;
-- 
2.55.0.508.g3f0d502094-goog