On Thu, Dec 06, 2018 at 05:31:25PM +0000, Marc Zyngier wrote: > In order to avoid TLB corruption whilst invalidating TLBs on CPUs > affected by erratum 1165522, we need to prevent S1 page tables > from being usable. > > For this, we set the EL1 S1 MMU on, and also disable the page table > walker (by setting the TCR_EL1.EPD* bits to 1). > > This ensures that once we switch to the EL1/EL0 translation regime, > speculated AT instructions won't be able to parse the page tables. > > Reviewed-by: James Morse <james.mo...@arm.com> > Signed-off-by: Marc Zyngier <marc.zyng...@arm.com> > --- > arch/arm64/kvm/hyp/tlb.c | 66 +++++++++++++++++++++++++++++++--------- > 1 file changed, 51 insertions(+), 15 deletions(-) > > diff --git a/arch/arm64/kvm/hyp/tlb.c b/arch/arm64/kvm/hyp/tlb.c > index 7fcc9c1a5f45..ec157543d5a9 100644 > --- a/arch/arm64/kvm/hyp/tlb.c > +++ b/arch/arm64/kvm/hyp/tlb.c > @@ -21,12 +21,36 @@ > #include <asm/kvm_mmu.h> > #include <asm/tlbflush.h> > > +struct tlb_inv_context { > + unsigned long flags; > + u64 tcr; > + u64 sctlr; > +}; > + > static void __hyp_text __tlb_switch_to_guest_vhe(struct kvm *kvm, > - unsigned long *flags) > + struct tlb_inv_context *cxt) > { > u64 val; > > - local_irq_save(*flags); > + local_irq_save(cxt->flags); > + > + if (cpus_have_const_cap(ARM64_WORKAROUND_1165522)) { > + /* > + * For CPUs that are affected by ARM erratum 1165522, we > + * cannot trust stage-1 to be in a correct state at that > + * point. Since we do not want to force a full load of the > + * vcpu state, we prevent the EL1 page-table walker to > + * allocate new TLBs. This is done by setting the EPD bits > + * in the TCR_EL1 register. We also need to prevent it to > + * allocate IPA->PA walks, so we enable the S1 MMU... > + */ > + val = cxt->tcr = read_sysreg_el1(tcr); > + val |= TCR_EPD1_MASK | TCR_EPD0_MASK; > + write_sysreg_el1(val, tcr); > + val = cxt->sctlr = read_sysreg_el1(sctlr); > + val |= SCTLR_ELx_M; > + write_sysreg_el1(val, sctlr); > + } > > /* > * With VHE enabled, we have HCR_EL2.{E2H,TGE} = {1,1}, and > @@ -34,6 +58,11 @@ static void __hyp_text __tlb_switch_to_guest_vhe(struct > kvm *kvm, > * guest TLBs (EL1/EL0), we need to change one of these two > * bits. Changing E2H is impossible (goodbye TTBR1_EL2), so > * let's flip TGE before executing the TLB operation. > + * > + * ARM erratum 1165522 requires some special handling (again), > + * as we need to make sure both stages of translation are in > + * place before clearing TGE. __load_guest_stage2() already > + * has an ISB in order to deal with this. > */ > __load_guest_stage2(kvm); > val = read_sysreg(hcr_el2); > @@ -43,7 +72,7 @@ static void __hyp_text __tlb_switch_to_guest_vhe(struct kvm > *kvm, > } > > static void __hyp_text __tlb_switch_to_guest_nvhe(struct kvm *kvm, > - unsigned long *flags) > + struct tlb_inv_context *cxt) > { > __load_guest_stage2(kvm); > isb(); > @@ -55,7 +84,7 @@ static hyp_alternate_select(__tlb_switch_to_guest, > ARM64_HAS_VIRT_HOST_EXTN); > > static void __hyp_text __tlb_switch_to_host_vhe(struct kvm *kvm, > - unsigned long flags) > + struct tlb_inv_context *cxt) > { > /* > * We're done with the TLB operation, let's restore the host's > @@ -64,11 +93,18 @@ static void __hyp_text __tlb_switch_to_host_vhe(struct > kvm *kvm, > write_sysreg(0, vttbr_el2); > write_sysreg(HCR_HOST_VHE_FLAGS, hcr_el2); > isb(); > - local_irq_restore(flags); > + > + if (cpus_have_const_cap(ARM64_WORKAROUND_1165522)) { > + /* Restore the guest's registers to what they were */
host's ? > + write_sysreg_el1(cxt->tcr, tcr); > + write_sysreg_el1(cxt->sctlr, sctlr); > + } > + > + local_irq_restore(cxt->flags); > } > > static void __hyp_text __tlb_switch_to_host_nvhe(struct kvm *kvm, > - unsigned long flags) > + struct tlb_inv_context *cxt) > { > write_sysreg(0, vttbr_el2); > } > @@ -80,13 +116,13 @@ static hyp_alternate_select(__tlb_switch_to_host, > > void __hyp_text __kvm_tlb_flush_vmid_ipa(struct kvm *kvm, phys_addr_t ipa) > { > - unsigned long flags; > + struct tlb_inv_context cxt; > > dsb(ishst); > > /* Switch to requested VMID */ > kvm = kern_hyp_va(kvm); > - __tlb_switch_to_guest()(kvm, &flags); > + __tlb_switch_to_guest()(kvm, &cxt); > > /* > * We could do so much better if we had the VA as well. > @@ -129,39 +165,39 @@ void __hyp_text __kvm_tlb_flush_vmid_ipa(struct kvm > *kvm, phys_addr_t ipa) > if (!has_vhe() && icache_is_vpipt()) > __flush_icache_all(); > > - __tlb_switch_to_host()(kvm, flags); > + __tlb_switch_to_host()(kvm, &cxt); > } > > void __hyp_text __kvm_tlb_flush_vmid(struct kvm *kvm) > { > - unsigned long flags; > + struct tlb_inv_context cxt; > > dsb(ishst); > > /* Switch to requested VMID */ > kvm = kern_hyp_va(kvm); > - __tlb_switch_to_guest()(kvm, &flags); > + __tlb_switch_to_guest()(kvm, &cxt); > > __tlbi(vmalls12e1is); > dsb(ish); > isb(); > > - __tlb_switch_to_host()(kvm, flags); > + __tlb_switch_to_host()(kvm, &cxt); > } > > void __hyp_text __kvm_tlb_flush_local_vmid(struct kvm_vcpu *vcpu) > { > struct kvm *kvm = kern_hyp_va(kern_hyp_va(vcpu)->kvm); > - unsigned long flags; > + struct tlb_inv_context cxt; > > /* Switch to requested VMID */ > - __tlb_switch_to_guest()(kvm, &flags); > + __tlb_switch_to_guest()(kvm, &cxt); > > __tlbi(vmalle1); > dsb(nsh); > isb(); > > - __tlb_switch_to_host()(kvm, flags); > + __tlb_switch_to_host()(kvm, &cxt); > } > > void __hyp_text __kvm_flush_vm_context(void) > -- > 2.19.2 > Otherwise: Acked-by: Christoffer Dall <christoffer.d...@arm.com> _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm