Commit 72db3d3f authored by Quentin Perret's avatar Quentin Perret Committed by Marc Zyngier
Browse files

KVM: arm64: Introduce __pkvm_host_unshare_guest() 



In preparation for letting the host unmap pages from non-protected
guests, introduce a new hypercall implementing the host-unshare-guest
transition.

Tested-by: default avatarFuad Tabba <tabba@google.com>
Reviewed-by: default avatarFuad Tabba <tabba@google.com>
Signed-off-by: default avatarQuentin Perret <qperret@google.com>
Link: https://lore.kernel.org/r/20241218194059.3670226-12-qperret@google.com


Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
parent d0bd3e65

arch/arm64/include/asm/kvm_asm.h

+1 −0
Original line number Diff line number Diff line
@@ -66,6 +66,7 @@ enum __kvm_host_smccc_func { 
	__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_unshare_guest,

	__KVM_HOST_SMCCC_FUNC___kvm_adjust_pc,

	__KVM_HOST_SMCCC_FUNC___kvm_vcpu_run,

	__KVM_HOST_SMCCC_FUNC___kvm_flush_vm_context,

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

+1 −0
Original line number Diff line number Diff line
@@ -41,6 +41,7 @@ int __pkvm_host_share_ffa(u64 pfn, u64 nr_pages); 
int __pkvm_host_unshare_ffa(u64 pfn, u64 nr_pages);

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);



bool addr_is_memory(phys_addr_t phys);

int host_stage2_idmap_locked(phys_addr_t addr, u64 size, enum kvm_pgtable_prot prot);

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

+6 −0
Original line number Diff line number Diff line
@@ -64,6 +64,11 @@ static inline bool pkvm_hyp_vcpu_is_protected(struct pkvm_hyp_vcpu *hyp_vcpu) 
	return vcpu_is_protected(&hyp_vcpu->vcpu);

}



static inline bool pkvm_hyp_vm_is_protected(struct pkvm_hyp_vm *hyp_vm)

{

	return kvm_vm_is_protected(&hyp_vm->kvm);

}



void pkvm_hyp_vm_table_init(void *tbl);



int __pkvm_init_vm(struct kvm *host_kvm, unsigned long vm_hva,
@@ -78,6 +83,7 @@ void pkvm_put_hyp_vcpu(struct pkvm_hyp_vcpu *hyp_vcpu); 
struct pkvm_hyp_vcpu *pkvm_get_loaded_hyp_vcpu(void);



struct pkvm_hyp_vm *get_pkvm_hyp_vm(pkvm_handle_t handle);

struct pkvm_hyp_vm *get_np_pkvm_hyp_vm(pkvm_handle_t handle);

void put_pkvm_hyp_vm(struct pkvm_hyp_vm *hyp_vm);



#endif /* __ARM64_KVM_NVHE_PKVM_H__ */

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

+21 −0
Original line number Diff line number Diff line
@@ -244,6 +244,26 @@ static void handle___pkvm_host_share_guest(struct kvm_cpu_context *host_ctxt) 
	cpu_reg(host_ctxt, 1) =  ret;

}



static void handle___pkvm_host_unshare_guest(struct kvm_cpu_context *host_ctxt)

{

	DECLARE_REG(pkvm_handle_t, handle, host_ctxt, 1);

	DECLARE_REG(u64, gfn, host_ctxt, 2);

	struct pkvm_hyp_vm *hyp_vm;

	int ret = -EINVAL;



	if (!is_protected_kvm_enabled())

		goto out;



	hyp_vm = get_np_pkvm_hyp_vm(handle);

	if (!hyp_vm)

		goto out;



	ret = __pkvm_host_unshare_guest(gfn, hyp_vm);

	put_pkvm_hyp_vm(hyp_vm);

out:

	cpu_reg(host_ctxt, 1) =  ret;

}



static void handle___kvm_adjust_pc(struct kvm_cpu_context *host_ctxt)

{

	DECLARE_REG(struct kvm_vcpu *, vcpu, host_ctxt, 1);
@@ -454,6 +474,7 @@ 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_unshare_guest),

	HANDLE_FUNC(__kvm_adjust_pc),

	HANDLE_FUNC(__kvm_vcpu_run),

	HANDLE_FUNC(__kvm_flush_vm_context),

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

+67 −0
Original line number Diff line number Diff line
@@ -1421,3 +1421,70 @@ int __pkvm_host_share_guest(u64 pfn, u64 gfn, struct pkvm_hyp_vcpu *vcpu, 


	return ret;

}



static int __check_host_shared_guest(struct pkvm_hyp_vm *vm, u64 *__phys, u64 ipa)

{

	enum pkvm_page_state state;

	struct hyp_page *page;

	kvm_pte_t pte;

	u64 phys;

	s8 level;

	int ret;



	ret = kvm_pgtable_get_leaf(&vm->pgt, ipa, &pte, &level);

	if (ret)

		return ret;

	if (level != KVM_PGTABLE_LAST_LEVEL)

		return -E2BIG;

	if (!kvm_pte_valid(pte))

		return -ENOENT;



	state = guest_get_page_state(pte, ipa);

	if (state != PKVM_PAGE_SHARED_BORROWED)

		return -EPERM;



	phys = kvm_pte_to_phys(pte);

	ret = check_range_allowed_memory(phys, phys + PAGE_SIZE);

	if (WARN_ON(ret))

		return ret;



	page = hyp_phys_to_page(phys);

	if (page->host_state != PKVM_PAGE_SHARED_OWNED)

		return -EPERM;

	if (WARN_ON(!page->host_share_guest_count))

		return -EINVAL;



	*__phys = phys;



	return 0;

}



int __pkvm_host_unshare_guest(u64 gfn, struct pkvm_hyp_vm *vm)

{

	u64 ipa = hyp_pfn_to_phys(gfn);

	struct hyp_page *page;

	u64 phys;

	int ret;



	host_lock_component();

	guest_lock_component(vm);



	ret = __check_host_shared_guest(vm, &phys, ipa);

	if (ret)

		goto unlock;



	ret = kvm_pgtable_stage2_unmap(&vm->pgt, ipa, PAGE_SIZE);

	if (ret)

		goto unlock;



	page = hyp_phys_to_page(phys);

	page->host_share_guest_count--;

	if (!page->host_share_guest_count)

		WARN_ON(__host_set_page_state_range(phys, PAGE_SIZE, PKVM_PAGE_OWNED));



unlock:

	guest_unlock_component(vm);

	host_unlock_component();



	return ret;

}