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KVM: arm64: Introduce __pkvm_host_donate_guest()

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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 <tabba@google.com>
Tested-by: Mostafa Saleh <smostafa@google.com>
Signed-off-by: Will Deacon <will@kernel.org>
Link: https://patch.msgid.link/20260330144841.26181-13-will@kernel.org
Signed-off-by: Marc Zyngier <maz@kernel.org>
This commit is contained in:
Will Deacon
2026-03-30 15:48:13 +01:00
committed by Marc Zyngier
parent 6c58f914eb
commit 1e579adca1
5 changed files with 55 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files

1
arch/arm64/include/asm/kvm_asm.h
View File

@@ -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,

2
arch/arm64/include/asm/kvm_pgtable.h
View File

@@ -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

2
arch/arm64/kvm/hyp/include/nvhe/mem_protect.h
View File

@@ -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);

21
arch/arm64/kvm/hyp/nvhe/hyp-main.c
View File

@@ -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),

30
arch/arm64/kvm/hyp/nvhe/mem_protect.c
View File

@@ -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)
{