Commit 1e579adc authored by Will Deacon's avatar Will Deacon Committed by Marc Zyngier
Browse files

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: default avatarFuad Tabba <tabba@google.com>
Tested-by: default avatarMostafa Saleh <smostafa@google.com>
Signed-off-by: default avatarWill Deacon <will@kernel.org>
Link: https://patch.msgid.link/20260330144841.26181-13-will@kernel.org


Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
parent 6c58f914

arch/arm64/include/asm/kvm_asm.h

+1 −0
Original line number Diff line number Diff line
@@ -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,

arch/arm64/include/asm/kvm_pgtable.h

+1 −1
Original line number Diff line number Diff line
@@ -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

arch/arm64/kvm/hyp/include/nvhe/mem_protect.h

+2 −0
Original line number Diff line number Diff line
@@ -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);

arch/arm64/kvm/hyp/nvhe/hyp-main.c

+21 −0
Original line number Diff line number Diff line
@@ -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),

arch/arm64/kvm/hyp/nvhe/mem_protect.c

+30 −0
Original line number Diff line number Diff line
@@ -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)

{