Commit 34884a0a authored by Quentin Perret's avatar Quentin Perret Committed by Marc Zyngier
Browse files

KVM: arm64: Introduce __pkvm_host_relax_guest_perms() 



Introduce a new hypercall allowing the host to relax the stage-2
permissions of mappings in a non-protected guest page-table. It will be
used later once we start allowing RO memslots and dirty logging.

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/20241218194059.3670226-13-qperret@google.com


Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
parent 72db3d3f

arch/arm64/include/asm/kvm_asm.h

+1 −0
Original line number Diff line number Diff line
@@ -67,6 +67,7 @@ enum __kvm_host_smccc_func { 
	__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___pkvm_host_relax_perms_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
@@ -42,6 +42,7 @@ 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);

int __pkvm_host_relax_perms_guest(u64 gfn, struct pkvm_hyp_vcpu *vcpu, enum kvm_pgtable_prot prot);



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

+20 −0
Original line number Diff line number Diff line
@@ -264,6 +264,25 @@ static void handle___pkvm_host_unshare_guest(struct kvm_cpu_context *host_ctxt) 
	cpu_reg(host_ctxt, 1) =  ret;

}



static void handle___pkvm_host_relax_perms_guest(struct kvm_cpu_context *host_ctxt)

{

	DECLARE_REG(u64, gfn, host_ctxt, 1);

	DECLARE_REG(enum kvm_pgtable_prot, prot, host_ctxt, 2);

	struct pkvm_hyp_vcpu *hyp_vcpu;

	int ret = -EINVAL;



	if (!is_protected_kvm_enabled())

		goto out;



	hyp_vcpu = pkvm_get_loaded_hyp_vcpu();

	if (!hyp_vcpu || pkvm_hyp_vcpu_is_protected(hyp_vcpu))

		goto out;



	ret = __pkvm_host_relax_perms_guest(gfn, hyp_vcpu, prot);

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);
@@ -475,6 +494,7 @@ static const hcall_t host_hcall[] = { 
	HANDLE_FUNC(__pkvm_host_unshare_hyp),

	HANDLE_FUNC(__pkvm_host_share_guest),

	HANDLE_FUNC(__pkvm_host_unshare_guest),

	HANDLE_FUNC(__pkvm_host_relax_perms_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

+23 −0
Original line number Diff line number Diff line
@@ -1488,3 +1488,26 @@ int __pkvm_host_unshare_guest(u64 gfn, struct pkvm_hyp_vm *vm) 


	return ret;

}



int __pkvm_host_relax_perms_guest(u64 gfn, struct pkvm_hyp_vcpu *vcpu, enum kvm_pgtable_prot prot)

{

	struct pkvm_hyp_vm *vm = pkvm_hyp_vcpu_to_hyp_vm(vcpu);

	u64 ipa = hyp_pfn_to_phys(gfn);

	u64 phys;

	int ret;



	if (prot & ~KVM_PGTABLE_PROT_RWX)

		return -EINVAL;



	host_lock_component();

	guest_lock_component(vm);



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

	if (!ret)

		ret = kvm_pgtable_stage2_relax_perms(&vm->pgt, ipa, prot, 0);



	guest_unlock_component(vm);

	host_unlock_component();



	return ret;

}