| Message ID | 20241216175803.2716565-17-qperret@google.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | KVM: arm64: Non-protected guest stage-2 support for pKVM | expand |
On Mon, 16 Dec 2024 at 17:58, Quentin Perret <qperret@google.com> wrote: > > 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. > > Signed-off-by: Quentin Perret <qperret@google.com> Reviewed-by: Fuad Tabba <tabba@google.com> Cheers, /fuad > --- > arch/arm64/include/asm/kvm_asm.h | 1 + > arch/arm64/kvm/hyp/nvhe/hyp-main.c | 17 +++++++++++++++++ > 2 files changed, 18 insertions(+) > > diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h > index a3b07db2776c..002088c6e297 100644 > --- a/arch/arm64/include/asm/kvm_asm.h > +++ b/arch/arm64/include/asm/kvm_asm.h > @@ -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[] > diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/hyp-main.c > index 32c4627b5b5b..130f5f23bcb5 100644 > --- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c > +++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c > @@ -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) > -- > 2.47.1.613.gc27f4b7a9f-goog >
diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h index a3b07db2776c..002088c6e297 100644 --- a/arch/arm64/include/asm/kvm_asm.h +++ b/arch/arm64/include/asm/kvm_asm.h @@ -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[] diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/hyp-main.c index 32c4627b5b5b..130f5f23bcb5 100644 --- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c +++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c @@ -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)
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. Signed-off-by: Quentin Perret <qperret@google.com> --- arch/arm64/include/asm/kvm_asm.h | 1 + arch/arm64/kvm/hyp/nvhe/hyp-main.c | 17 +++++++++++++++++ 2 files changed, 18 insertions(+)