On 25/01/16 16:26, Will Deacon wrote: > On Mon, Jan 25, 2016 at 03:53:34PM +0000, Marc Zyngier wrote: >> ARMv8.1 comes with the "Virtualization Host Extension" (VHE for >> short), which enables simpler support of Type-2 hypervisors. >> >> This extension allows the kernel to directly run at EL2, and >> significantly reduces the number of system registers shared between >> host and guest, reducing the overhead of virtualization. >> >> In order to have the same kernel binary running on all versions of the >> architecture, this series makes heavy use of runtime code patching. >> >> The first 20 patches massage the KVM code to deal with VHE and enable >> Linux to run at EL2. The last patch catches an ugly case when VHE >> capable CPUs are paired with some of their less capable siblings. This >> should never happen, but hey... >> >> I have deliberately left out some of the more "advanced" >> optimizations, as they are likely to distract the reviewer from the >> core infrastructure, which is what I care about at the moment. >> >> A few things to note: >> >> - Given that the code has been almost entierely rewritten, I've >> dropped all Acks from the new patches >> >> - GDB is currently busted on VHE systems, as it checks for version 6 >> on the debug architecture, while VHE is version 7. The binutils >> people are on the case. > > [...] > >> arch/arm/include/asm/virt.h | 5 ++ >> arch/arm/kvm/arm.c | 151 +++++++++++++++++++------------ >> arch/arm/kvm/mmu.c | 7 ++ >> arch/arm64/Kconfig | 13 +++ >> arch/arm64/include/asm/cpufeature.h | 3 +- >> arch/arm64/include/asm/kvm_arm.h | 1 + >> arch/arm64/include/asm/kvm_emulate.h | 3 + >> arch/arm64/include/asm/kvm_mmu.h | 34 ++++++- >> arch/arm64/include/asm/virt.h | 27 ++++++ >> arch/arm64/kernel/asm-offsets.c | 3 - >> arch/arm64/kernel/cpufeature.c | 15 +++- >> arch/arm64/kernel/head.S | 51 ++++++++++- >> arch/arm64/kernel/smp.c | 3 + >> arch/arm64/kvm/hyp-init.S | 18 +--- >> arch/arm64/kvm/hyp.S | 7 ++ >> arch/arm64/kvm/hyp/entry.S | 6 ++ >> arch/arm64/kvm/hyp/hyp-entry.S | 107 +++++++--------------- >> arch/arm64/kvm/hyp/hyp.h | 119 ++++++++++++++++++++++-- >> arch/arm64/kvm/hyp/switch.c | 170 +++++++++++++++++++++++++++++++---- >> arch/arm64/kvm/hyp/sysreg-sr.c | 147 ++++++++++++++++++++---------- >> arch/arm64/kvm/hyp/timer-sr.c | 10 +-- >> drivers/clocksource/arm_arch_timer.c | 96 ++++++++++++-------- >> 22 files changed, 724 insertions(+), 272 deletions(-) > > Have you tried hw_breakpoint/perf/ptrace with these changes? I was under > the impression that the debug architecture was aware of E2H and did need > some changes made. I know you say that GDB is broken anyway, but we should > check that the kernel does the right thing if userspace pokes it the > right way. I did use HW breakpoints on the model by hacking the host kernel to return Debug Version 6 instead of 7, and things seem to work as expected. strace also works out of the box. As for perf, did you have something precise in mind? Thanks, M. -- Jazz is not dead. It just smells funny... -- 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
