Commit b8cc6eb5 authored by Will Deacon's avatar Will Deacon Committed by Marc Zyngier
Browse files

KVM: arm64: Expose unshare hypercall to the host 



Introduce an unshare hypercall which can be used to unmap memory from
the hypervisor stage-1 in nVHE protected mode. This will be useful to
update the EL2 ownership state of pages during guest teardown, and
avoids keeping dangling mappings to unreferenced portions of memory.

Signed-off-by: default avatarWill Deacon <will@kernel.org>
Signed-off-by: default avatarQuentin Perret <qperret@google.com>
Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20211215161232.1480836-14-qperret@google.com
parent 376a240f

arch/arm64/include/asm/kvm_asm.h

+1 −0
Original line number Diff line number Diff line
@@ -63,6 +63,7 @@ enum __kvm_host_smccc_func { 


	/* Hypercalls available after pKVM finalisation */

	__KVM_HOST_SMCCC_FUNC___pkvm_host_share_hyp,

	__KVM_HOST_SMCCC_FUNC___pkvm_host_unshare_hyp,

	__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
@@ -55,6 +55,7 @@ extern const u8 pkvm_hyp_id; 


int __pkvm_prot_finalize(void);

int __pkvm_host_share_hyp(u64 pfn);

int __pkvm_host_unshare_hyp(u64 pfn);



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/hyp-main.c

+8 −0
Original line number Diff line number Diff line
@@ -147,6 +147,13 @@ static void handle___pkvm_host_share_hyp(struct kvm_cpu_context *host_ctxt) 
	cpu_reg(host_ctxt, 1) = __pkvm_host_share_hyp(pfn);

}



static void handle___pkvm_host_unshare_hyp(struct kvm_cpu_context *host_ctxt)

{

	DECLARE_REG(u64, pfn, host_ctxt, 1);



	cpu_reg(host_ctxt, 1) = __pkvm_host_unshare_hyp(pfn);

}



static void handle___pkvm_create_private_mapping(struct kvm_cpu_context *host_ctxt)

{

	DECLARE_REG(phys_addr_t, phys, host_ctxt, 1);
@@ -184,6 +191,7 @@ static const hcall_t host_hcall[] = { 
	HANDLE_FUNC(__pkvm_prot_finalize),



	HANDLE_FUNC(__pkvm_host_share_hyp),

	HANDLE_FUNC(__pkvm_host_unshare_hyp),

	HANDLE_FUNC(__kvm_adjust_pc),

	HANDLE_FUNC(__kvm_vcpu_run),

	HANDLE_FUNC(__kvm_flush_vm_context),

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

+33 −0
Original line number Diff line number Diff line
@@ -768,3 +768,36 @@ int __pkvm_host_share_hyp(u64 pfn) 


	return ret;

}



int __pkvm_host_unshare_hyp(u64 pfn)

{

	int ret;

	u64 host_addr = hyp_pfn_to_phys(pfn);

	u64 hyp_addr = (u64)__hyp_va(host_addr);

	struct pkvm_mem_share share = {

		.tx	= {

			.nr_pages	= 1,

			.initiator	= {

				.id	= PKVM_ID_HOST,

				.addr	= host_addr,

				.host	= {

					.completer_addr = hyp_addr,

				},

			},

			.completer	= {

				.id	= PKVM_ID_HYP,

			},

		},

		.completer_prot	= PAGE_HYP,

	};



	host_lock_component();

	hyp_lock_component();



	ret = do_unshare(&share);



	hyp_unlock_component();

	host_unlock_component();



	return ret;

}