On 25/01/16 16:44, Will Deacon wrote: > 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). So indeed these didn't work (perf reported 0 for kernel accesses). The fixes are pretty trivial, and I've put them on top of my kvm-arm64/vhe branch, for those who want to have a look. 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
