Commit f9112ead authored by Will Deacon's avatar Will Deacon Committed by Oliver Upton
Browse files

KVM: arm64: Add FF-A helpers to share/unshare memory with secure world 



Extend pKVM's memory protection code so that we can update the host's
stage-2 page-table to track pages shared with secure world by the host
using FF-A and prevent those pages from being mapped into a guest.

Co-developed-by: default avatarAndrew Walbran <qwandor@google.com>
Signed-off-by: default avatarAndrew Walbran <qwandor@google.com>
Signed-off-by: default avatarWill Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20230523101828.7328-6-will@kernel.org


Signed-off-by: default avatarOliver Upton <oliver.upton@linux.dev>
parent 9d0c6a9a

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

+3 −0
Original line number Diff line number Diff line
@@ -57,6 +57,7 @@ extern struct host_mmu host_mmu; 
enum pkvm_component_id {

	PKVM_ID_HOST,

	PKVM_ID_HYP,

	PKVM_ID_FFA,

};



extern unsigned long hyp_nr_cpus;
@@ -66,6 +67,8 @@ int __pkvm_host_share_hyp(u64 pfn); 
int __pkvm_host_unshare_hyp(u64 pfn);

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);



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/nvhe/mem_protect.c

+68 −0
Original line number Diff line number Diff line
@@ -842,6 +842,13 @@ static int check_share(struct pkvm_mem_share *share) 
	case PKVM_ID_HYP:

		ret = hyp_ack_share(completer_addr, tx, share->completer_prot);

		break;

	case PKVM_ID_FFA:

		/*

		 * We only check the host; the secure side will check the other

		 * end when we forward the FFA call.

		 */

		ret = 0;

		break;

	default:

		ret = -EINVAL;

	}
@@ -870,6 +877,13 @@ static int __do_share(struct pkvm_mem_share *share) 
	case PKVM_ID_HYP:

		ret = hyp_complete_share(completer_addr, tx, share->completer_prot);

		break;

	case PKVM_ID_FFA:

		/*

		 * We're not responsible for any secure page-tables, so there's

		 * nothing to do here.

		 */

		ret = 0;

		break;

	default:

		ret = -EINVAL;

	}
@@ -918,6 +932,10 @@ static int check_unshare(struct pkvm_mem_share *share) 
	case PKVM_ID_HYP:

		ret = hyp_ack_unshare(completer_addr, tx);

		break;

	case PKVM_ID_FFA:

		/* See check_share() */

		ret = 0;

		break;

	default:

		ret = -EINVAL;

	}
@@ -946,6 +964,10 @@ static int __do_unshare(struct pkvm_mem_share *share) 
	case PKVM_ID_HYP:

		ret = hyp_complete_unshare(completer_addr, tx);

		break;

	case PKVM_ID_FFA:

		/* See __do_share() */

		ret = 0;

		break;

	default:

		ret = -EINVAL;

	}
@@ -1235,3 +1257,49 @@ void hyp_unpin_shared_mem(void *from, void *to) 
	hyp_unlock_component();

	host_unlock_component();

}



int __pkvm_host_share_ffa(u64 pfn, u64 nr_pages)

{

	int ret;

	struct pkvm_mem_share share = {

		.tx	= {

			.nr_pages	= nr_pages,

			.initiator	= {

				.id	= PKVM_ID_HOST,

				.addr	= hyp_pfn_to_phys(pfn),

			},

			.completer	= {

				.id	= PKVM_ID_FFA,

			},

		},

	};



	host_lock_component();

	ret = do_share(&share);

	host_unlock_component();



	return ret;

}



int __pkvm_host_unshare_ffa(u64 pfn, u64 nr_pages)

{

	int ret;

	struct pkvm_mem_share share = {

		.tx	= {

			.nr_pages	= nr_pages,

			.initiator	= {

				.id	= PKVM_ID_HOST,

				.addr	= hyp_pfn_to_phys(pfn),

			},

			.completer	= {

				.id	= PKVM_ID_FFA,

			},

		},

	};



	host_lock_component();

	ret = do_unshare(&share);

	host_unlock_component();



	return ret;

}