KVM: arm64: Introduce hypercall for host-to-guest donations
In preparation for supporting protected guests, introduce a new memory
transition hypercall allowing the donation of pages to pVMs.
Signed-off-by: Quentin Perret <qperret@google.com>
diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h
index 6d3d11f..45d7141 100644
--- a/arch/arm64/include/asm/kvm_asm.h
+++ b/arch/arm64/include/asm/kvm_asm.h
@@ -64,7 +64,7 @@ enum __kvm_host_smccc_func {
/* Hypercalls available after pKVM finalisation */
__KVM_HOST_SMCCC_FUNC___pkvm_host_share_hyp,
__KVM_HOST_SMCCC_FUNC___pkvm_host_unshare_hyp,
- __KVM_HOST_SMCCC_FUNC___pkvm_host_share_guest,
+ __KVM_HOST_SMCCC_FUNC___pkvm_host_map_guest,
__KVM_HOST_SMCCC_FUNC___pkvm_host_unshare_guest,
__KVM_HOST_SMCCC_FUNC___pkvm_host_relax_perms_guest,
__KVM_HOST_SMCCC_FUNC___pkvm_host_wrprotect_guest,
diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h
index 6b9d274..adf7f4b 100644
--- a/arch/arm64/include/asm/kvm_pgtable.h
+++ b/arch/arm64/include/asm/kvm_pgtable.h
@@ -93,7 +93,7 @@ typedef u64 kvm_pte_t;
KVM_PTE_LEAF_ATTR_HI_S2_XN)
#define KVM_INVALID_PTE_OWNER_MASK GENMASK(9, 2)
-#define KVM_MAX_OWNER_ID 1
+#define KVM_MAX_OWNER_ID 3
/*
* Used to indicate a pte for which a 'break-before-make' sequence is in
diff --git a/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h b/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h
index ea0a704..15fabb7 100644
--- a/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h
+++ b/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h
@@ -28,6 +28,7 @@ enum pkvm_component_id {
PKVM_ID_HOST,
PKVM_ID_HYP,
PKVM_ID_FFA,
+ PKVM_ID_GUEST,
};
extern unsigned long hyp_nr_cpus;
@@ -39,6 +40,7 @@ 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_donate_guest(u64 pfn, u64 gfn, struct pkvm_hyp_vcpu *vcpu);
int __pkvm_host_share_guest(u64 pfn, u64 gfn, struct pkvm_hyp_vcpu *vcpu,
enum kvm_pgtable_prot prot);
int __pkvm_host_unshare_guest(u64 gfn, struct pkvm_hyp_vm *hyp_vm);
diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
index d60303c..688da95 100644
--- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c
+++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
@@ -777,7 +777,7 @@ static int pkvm_refill_memcache(struct pkvm_hyp_vcpu *hyp_vcpu)
&host_vcpu->arch.pkvm_memcache);
}
-static void handle___pkvm_host_share_guest(struct kvm_cpu_context *host_ctxt)
+static void handle___pkvm_host_map_guest(struct kvm_cpu_context *host_ctxt)
{
DECLARE_REG(u64, pfn, host_ctxt, 1);
DECLARE_REG(u64, gfn, host_ctxt, 2);
@@ -789,14 +789,17 @@ static void handle___pkvm_host_share_guest(struct kvm_cpu_context *host_ctxt)
goto out;
hyp_vcpu = pkvm_get_loaded_hyp_vcpu();
- if (!hyp_vcpu || pkvm_hyp_vcpu_is_protected(hyp_vcpu))
+ if (!hyp_vcpu)
goto out;
ret = pkvm_refill_memcache(hyp_vcpu);
if (ret)
goto out;
- ret = __pkvm_host_share_guest(pfn, gfn, hyp_vcpu, prot);
+ if (pkvm_hyp_vcpu_is_protected(hyp_vcpu))
+ ret = __pkvm_host_donate_guest(pfn, gfn, hyp_vcpu);
+ else
+ ret = __pkvm_host_share_guest(pfn, gfn, hyp_vcpu, prot);
out:
cpu_reg(host_ctxt, 1) = ret;
}
@@ -1131,7 +1134,7 @@ static const hcall_t host_hcall[] = {
HANDLE_FUNC(__pkvm_host_share_hyp),
HANDLE_FUNC(__pkvm_host_unshare_hyp),
- HANDLE_FUNC(__pkvm_host_share_guest),
+ HANDLE_FUNC(__pkvm_host_map_guest),
HANDLE_FUNC(__pkvm_host_unshare_guest),
HANDLE_FUNC(__pkvm_host_relax_perms_guest),
HANDLE_FUNC(__pkvm_host_wrprotect_guest),
diff --git a/arch/arm64/kvm/hyp/nvhe/mem_protect.c b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
index 1055f05..72a540d 100644
--- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c
+++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
@@ -935,6 +935,36 @@ int __pkvm_host_unshare_ffa(u64 pfn, u64 nr_pages)
return ret;
}
+int __pkvm_host_donate_guest(u64 pfn, u64 gfn, struct pkvm_hyp_vcpu *vcpu)
+{
+ struct pkvm_hyp_vm *vm = pkvm_hyp_vcpu_to_hyp_vm(vcpu);
+ u64 phys = hyp_pfn_to_phys(pfn);
+ u64 ipa = hyp_pfn_to_phys(gfn);
+ int ret;
+
+ host_lock_component();
+ guest_lock_component(vm);
+
+ ret = __host_check_page_state_range(phys, PAGE_SIZE, PKVM_PAGE_OWNED);
+ if (ret)
+ goto unlock;
+
+ ret = __guest_check_page_state_range(vcpu, ipa, PAGE_SIZE, PKVM_NOPAGE);
+ if (ret)
+ goto unlock;
+
+ WARN_ON(host_stage2_set_owner_locked(phys, PAGE_SIZE, PKVM_ID_GUEST));
+ WARN_ON(kvm_pgtable_stage2_map(&vm->pgt, ipa, PAGE_SIZE, phys,
+ pkvm_mkstate(KVM_PGTABLE_PROT_RWX, PKVM_PAGE_OWNED),
+ &vcpu->vcpu.arch.pkvm_memcache, 0));
+
+unlock:
+ guest_unlock_component(vm);
+ host_unlock_component();
+
+ return ret;
+}
+
int __pkvm_host_share_guest(u64 pfn, u64 gfn, struct pkvm_hyp_vcpu *vcpu,
enum kvm_pgtable_prot prot)
{
diff --git a/arch/arm64/kvm/pkvm.c b/arch/arm64/kvm/pkvm.c
index 0f89157..0906b63 100644
--- a/arch/arm64/kvm/pkvm.c
+++ b/arch/arm64/kvm/pkvm.c
@@ -364,7 +364,7 @@ int pkvm_pgtable_stage2_map(struct kvm_pgtable *pgt, u64 addr, u64 size,
return -EINVAL;
lockdep_assert_held_write(&kvm->mmu_lock);
- ret = kvm_call_hyp_nvhe(__pkvm_host_share_guest, pfn, gfn, prot);
+ ret = kvm_call_hyp_nvhe(__pkvm_host_map_guest, pfn, gfn, prot);
if (ret) {
/* Is the gfn already mapped due to a racing vCPU? */
if (ret == -EPERM)
