On Tue, Jun 07, 2016 at 11:58:20AM +0100, Marc Zyngier wrote: > Until now, we've been setting up KVM using two sets of page tables: > one for the "boot" where we perform the basic MMU setup, and one for > the runtime. > > Switching between the two was though to be safe, but we've recently > realized that it is not: it is not enough to ensure that the VA->PA > mapping is consistent when switching TTBR0_EL2, but we also have to > ensure that the intermediate translations are the same as well. If the > TLB can return two different values for intermediate translations, > we're screwed (TLB conflicts). Just a clarification: Intermediate Translations here means the page table levels of translations for a single stage of translation? Is there a valid reference to the arhictecture specification for this? Thanks, -Christoffer > > At that point, the only safe thing to do is to never change TTBR0_EL2, > which means that we need to make the idmap page part of the runtime > page tables. > > The series starts with a bit of brain dumping explaining what we're > trying to do. This might not be useful as a merge candidate, but it > was useful for me to put this somewhere. It goes on revamping the > whole notion of HYP VA range, making it runtime patchable. It then > always merge idmap and runtime page table into one set, leading to > quite a lot of simplification in the init/teardown code. In the > process, 32bit KVM gains the ability to teardown the HYP page-tables > and vectors, which makes kexec a bit closer. > > This has been tested on Seattle, Juno, the FVP model (both v8.0 and > v8.1), Cubietruck and Midway, and is based on 4.7-rc2. > > Thanks, > > M. > > Marc Zyngier (15): > arm64: KVM: Merged page tables documentation > arm64: KVM: Kill HYP_PAGE_OFFSET > arm64: Add ARM64_HYP_OFFSET_LOW capability > arm64: KVM: Define HYP offset masks > arm64: KVM: Refactor kern_hyp_va/hyp_kern_va to deal with multiple > offsets > arm/arm64: KVM: Export __hyp_text_start/end symbols > arm64: KVM: Runtime detection of lower HYP offset > arm/arm64: KVM: Always have merged page tables > arm64: KVM: Simplify HYP init/teardown > arm/arm64: KVM: Drop boot_pgd > arm/arm64: KVM: Kill free_boot_hyp_pgd > arm: KVM: Simplify HYP init > arm: KVM: Allow hyp teardown > arm/arm64: KVM: Prune unused #defines > arm/arm64: KVM: Check that IDMAP doesn't intersect with VA range > > arch/arm/include/asm/kvm_asm.h | 2 + > arch/arm/include/asm/kvm_host.h | 25 +++----- > arch/arm/include/asm/kvm_mmu.h | 11 ---- > arch/arm/include/asm/virt.h | 4 ++ > arch/arm/kvm/arm.c | 20 ++---- > arch/arm/kvm/init.S | 56 ++++++---------- > arch/arm/kvm/mmu.c | 125 ++++++++++++++++-------------------- > arch/arm64/include/asm/cpufeature.h | 3 +- > arch/arm64/include/asm/kvm_host.h | 17 ++--- > arch/arm64/include/asm/kvm_hyp.h | 28 ++++---- > arch/arm64/include/asm/kvm_mmu.h | 100 ++++++++++++++++++++++++----- > arch/arm64/include/asm/virt.h | 4 ++ > arch/arm64/kernel/cpufeature.c | 19 ++++++ > arch/arm64/kvm/hyp-init.S | 61 +++--------------- > arch/arm64/kvm/hyp/entry.S | 19 ------ > arch/arm64/kvm/hyp/hyp-entry.S | 15 +++++ > arch/arm64/kvm/reset.c | 28 -------- > 17 files changed, 240 insertions(+), 297 deletions(-) > > -- > 2.1.4 > -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
