From: Will Deacon Date: Mon, 30 Mar 2026 14:48:13 +0000 (+0100) Subject: KVM: arm64: Introduce __pkvm_host_donate_guest() X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=1e579adca1774b3713d1efa67d92a88ec86c04fa;p=thirdparty%2Fkernel%2Fstable.git KVM: arm64: Introduce __pkvm_host_donate_guest() In preparation for supporting protected VMs, whose memory pages are isolated from the host, introduce a new pKVM hypercall to allow the donation of pages to a guest. Tested-by: Fuad Tabba Tested-by: Mostafa Saleh Signed-off-by: Will Deacon Link: https://patch.msgid.link/20260330144841.26181-13-will@kernel.org Signed-off-by: Marc Zyngier --- diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h index df6b661701b6..dfc6625c8269 100644 --- a/arch/arm64/include/asm/kvm_asm.h +++ b/arch/arm64/include/asm/kvm_asm.h @@ -79,6 +79,7 @@ enum __kvm_host_smccc_func { /* Hypercalls that are available only when pKVM has finalised. */ __KVM_HOST_SMCCC_FUNC___pkvm_host_share_hyp, __KVM_HOST_SMCCC_FUNC___pkvm_host_unshare_hyp, + __KVM_HOST_SMCCC_FUNC___pkvm_host_donate_guest, __KVM_HOST_SMCCC_FUNC___pkvm_host_share_guest, __KVM_HOST_SMCCC_FUNC___pkvm_host_unshare_guest, __KVM_HOST_SMCCC_FUNC___pkvm_host_relax_perms_guest, diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h index c201168f2857..50caca311ef5 100644 --- a/arch/arm64/include/asm/kvm_pgtable.h +++ b/arch/arm64/include/asm/kvm_pgtable.h @@ -100,7 +100,7 @@ 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 2 /* * 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 7f25f2bca90c..7061b0be340a 100644 --- a/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h +++ b/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h @@ -27,6 +27,7 @@ extern struct host_mmu host_mmu; enum pkvm_component_id { PKVM_ID_HOST, PKVM_ID_HYP, + PKVM_ID_GUEST, }; extern unsigned long hyp_nr_cpus; @@ -38,6 +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_donate_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, u64 nr_pages, 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 634ea2766240..970656318cf2 100644 --- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c +++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c @@ -241,6 +241,26 @@ static int pkvm_refill_memcache(struct pkvm_hyp_vcpu *hyp_vcpu) &host_vcpu->arch.pkvm_memcache); } +static void handle___pkvm_host_donate_guest(struct kvm_cpu_context *host_ctxt) +{ + DECLARE_REG(u64, pfn, host_ctxt, 1); + DECLARE_REG(u64, gfn, host_ctxt, 2); + struct pkvm_hyp_vcpu *hyp_vcpu; + int ret = -EINVAL; + + hyp_vcpu = pkvm_get_loaded_hyp_vcpu(); + if (!hyp_vcpu || !pkvm_hyp_vcpu_is_protected(hyp_vcpu)) + goto out; + + ret = pkvm_refill_memcache(hyp_vcpu); + if (ret) + goto out; + + ret = __pkvm_host_donate_guest(pfn, gfn, hyp_vcpu); +out: + cpu_reg(host_ctxt, 1) = ret; +} + static void handle___pkvm_host_share_guest(struct kvm_cpu_context *host_ctxt) { DECLARE_REG(u64, pfn, host_ctxt, 1); @@ -595,6 +615,7 @@ static const hcall_t host_hcall[] = { HANDLE_FUNC(__pkvm_host_share_hyp), HANDLE_FUNC(__pkvm_host_unshare_hyp), + HANDLE_FUNC(__pkvm_host_donate_guest), HANDLE_FUNC(__pkvm_host_share_guest), HANDLE_FUNC(__pkvm_host_unshare_guest), HANDLE_FUNC(__pkvm_host_relax_perms_guest), diff --git a/arch/arm64/kvm/hyp/nvhe/mem_protect.c b/arch/arm64/kvm/hyp/nvhe/mem_protect.c index 7d22893ab1dc..03e6fa124253 100644 --- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c +++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c @@ -971,6 +971,36 @@ static int __guest_check_transition_size(u64 phys, u64 ipa, u64 nr_pages, u64 *s return 0; } +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(vm, 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, u64 nr_pages, struct pkvm_hyp_vcpu *vcpu, enum kvm_pgtable_prot prot) {