On Mon, Jan 25, 2016 at 04:37:39PM +0000, Marc Zyngier wrote: > 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? It would be worth trying things like the filter options on perf events (perf stat -e cycles:k to count cycles in kernel space) and also breakpoints (perf stat -e mem:<addr>:rwx on kernel addresses). Will -- 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
