Commit 0adce4d4 authored by Quentin Perret's avatar Quentin Perret Committed by Marc Zyngier
Browse files

KVM: arm64: Introduce __pkvm_tlb_flush_vmid() 



Introduce a new hypercall to flush the TLBs of non-protected guests. The
host kernel will be responsible for issuing this hypercall after changing
stage-2 permissions using the __pkvm_host_relax_guest_perms() or
__pkvm_host_wrprotect_guest() paths. This is left under the host's
responsibility for performance reasons.

Note however that the TLB maintenance for all *unmap* operations still
remains entirely under the hypervisor's responsibility for security
reasons -- an unmapped page may be donated to another entity, so a stale
TLB entry could be used to leak private data.

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/20241218194059.3670226-17-qperret@google.com


Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
parent 76f0b18b

arch/arm64/include/asm/kvm_asm.h

+1 −0
Original line number Diff line number Diff line
@@ -87,6 +87,7 @@ enum __kvm_host_smccc_func { 
	__KVM_HOST_SMCCC_FUNC___pkvm_teardown_vm,

	__KVM_HOST_SMCCC_FUNC___pkvm_vcpu_load,

	__KVM_HOST_SMCCC_FUNC___pkvm_vcpu_put,

	__KVM_HOST_SMCCC_FUNC___pkvm_tlb_flush_vmid,

};



#define DECLARE_KVM_VHE_SYM(sym)	extern char sym[]

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

+17 −0
Original line number Diff line number Diff line
@@ -389,6 +389,22 @@ static void handle___kvm_tlb_flush_vmid(struct kvm_cpu_context *host_ctxt) 
	__kvm_tlb_flush_vmid(kern_hyp_va(mmu));

}



static void handle___pkvm_tlb_flush_vmid(struct kvm_cpu_context *host_ctxt)

{

	DECLARE_REG(pkvm_handle_t, handle, host_ctxt, 1);

	struct pkvm_hyp_vm *hyp_vm;



	if (!is_protected_kvm_enabled())

		return;



	hyp_vm = get_np_pkvm_hyp_vm(handle);

	if (!hyp_vm)

		return;



	__kvm_tlb_flush_vmid(&hyp_vm->kvm.arch.mmu);

	put_pkvm_hyp_vm(hyp_vm);

}



static void handle___kvm_flush_cpu_context(struct kvm_cpu_context *host_ctxt)

{

	DECLARE_REG(struct kvm_s2_mmu *, mmu, host_ctxt, 1);
@@ -573,6 +589,7 @@ static const hcall_t host_hcall[] = { 
	HANDLE_FUNC(__pkvm_teardown_vm),

	HANDLE_FUNC(__pkvm_vcpu_load),

	HANDLE_FUNC(__pkvm_vcpu_put),

	HANDLE_FUNC(__pkvm_tlb_flush_vmid),

};



static void handle_host_hcall(struct kvm_cpu_context *host_ctxt)