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Message-ID: <871t7vjttr.fsf@linaro.org> Date: Mon, 29 Feb 2016 17:43:28 +0000 From: Alex Bennée <alex.bennee@...aro.org> To: Marc Zyngier <marc.zyngier@....com> Cc: Catalin Marinas <catalin.marinas@....com>, Will Deacon <will.deacon@....com>, Mark Rutland <mark.rutland@....com>, Christoffer Dall <christoffer.dall@...aro.org>, kvmarm@...ts.cs.columbia.edu, linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, kvm@...r.kernel.org Subject: Re: [PATCH v4 00/23] arm64: Virtualization Host Extension support Marc Zyngier <marc.zyngier@....com> writes: > 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 22 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. > > Note: 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. I assume you are talking about ptrace debug here rather than guest debug? Anyway from a cursory inspection I didn't see anything to worry about from the guest debug side which is unchanged. Acked-by: Alex Bennée <alex.bennee@...aro.org> > > This has been tested on the FVP_Base_SLV-V8-A model, and based on > v4.5-rc3 + kvmarm/master. I've put a branch out on: > > git://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git kvm-arm64/vhe > > * From v3: > - Cleaned debug handling after comments from Catalin > - Added missing barriers in the panic patch > - Collected Rb and Acks from Christoffer and Catalin > > * From v2: > - Added support for perf to count kernel events in EL2 > - Added support for EL2 breakpoints > - Moved the VTCR_EL2 setup from assembly to C > - Made the fault handling easier to understand (hopefuly) > - Plenty of smaller fixups > > * From v1: > - Full rewrite now that the World Switch is written in C code. > - Dropped the "early IRQ handling" for the moment. > > Marc Zyngier (23): > arm/arm64: KVM: Add hook for C-based stage2 init > arm64: KVM: Switch to C-based stage2 init > arm/arm64: Add new is_kernel_in_hyp_mode predicate > arm64: Allow the arch timer to use the HYP timer > arm64: Add ARM64_HAS_VIRT_HOST_EXTN feature > arm64: KVM: Skip HYP setup when already running in HYP > arm64: KVM: VHE: Patch out use of HVC > arm64: KVM: VHE: Patch out kern_hyp_va > arm64: KVM: VHE: Introduce unified system register accessors > arm64: KVM: VHE: Differenciate host/guest sysreg save/restore > arm64: KVM: VHE: Split save/restore of registers shared between guest > and host > arm64: KVM: VHE: Use unified system register accessors > arm64: KVM: VHE: Enable minimal sysreg save/restore > arm64: KVM: VHE: Make __fpsimd_enabled VHE aware > arm64: KVM: VHE: Implement VHE activate/deactivate_traps > arm64: KVM: VHE: Use unified sysreg accessors for timer > arm64: KVM: VHE: Add fpsimd enabling on guest access > arm64: KVM: VHE: Add alternative panic handling > arm64: KVM: Move most of the fault decoding to C > arm64: perf: Count EL2 events if the kernel is running in HYP > arm64: hw_breakpoint: Allow EL2 breakpoints if running in HYP > arm64: VHE: Add support for running Linux in EL2 mode > arm64: Panic when VHE and non VHE CPUs coexist > > arch/arm/include/asm/kvm_host.h | 4 + > arch/arm/include/asm/virt.h | 5 + > arch/arm/kvm/arm.c | 174 ++++++++++++++++++---------- > arch/arm/kvm/mmu.c | 7 ++ > arch/arm64/Kconfig | 13 +++ > arch/arm64/include/asm/cpufeature.h | 3 +- > arch/arm64/include/asm/hw_breakpoint.h | 49 +++++--- > arch/arm64/include/asm/kvm_arm.h | 6 +- > arch/arm64/include/asm/kvm_asm.h | 2 + > arch/arm64/include/asm/kvm_emulate.h | 3 + > arch/arm64/include/asm/kvm_host.h | 6 + > arch/arm64/include/asm/kvm_mmu.h | 12 +- > arch/arm64/include/asm/virt.h | 27 +++++ > arch/arm64/kernel/asm-offsets.c | 3 - > arch/arm64/kernel/cpufeature.c | 11 ++ > arch/arm64/kernel/head.S | 50 +++++++- > arch/arm64/kernel/perf_event.c | 14 ++- > arch/arm64/kernel/smp.c | 3 + > arch/arm64/kvm/hyp-init.S | 18 --- > arch/arm64/kvm/hyp.S | 7 ++ > arch/arm64/kvm/hyp/Makefile | 1 + > arch/arm64/kvm/hyp/entry.S | 6 + > arch/arm64/kvm/hyp/hyp-entry.S | 109 ++++++------------ > arch/arm64/kvm/hyp/hyp.h | 108 ++++++++++++++++-- > arch/arm64/kvm/hyp/s2-setup.c | 44 +++++++ > arch/arm64/kvm/hyp/switch.c | 202 +++++++++++++++++++++++++++++---- > arch/arm64/kvm/hyp/sysreg-sr.c | 147 ++++++++++++++++-------- > arch/arm64/kvm/hyp/timer-sr.c | 10 +- > drivers/clocksource/arm_arch_timer.c | 96 ++++++++++------ > 29 files changed, 842 insertions(+), 298 deletions(-) > create mode 100644 arch/arm64/kvm/hyp/s2-setup.c -- Alex Bennée
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