Re: [PATCH 0/9] arm64: Stolen time support

zhukeqian
2020-07-21T03:26:47Z

Hi Steven,

On 2019/8/2 22:50, Steven Price wrote:
> This series add support for paravirtualized time for arm64 guests and
> KVM hosts following the specification in Arm's document DEN 0057A:
>
> https://developer.arm.com/docs/den0057/a
>
> It implements support for stolen time, allowing the guest to
> identify time when it is forcibly not executing.
>
> It doesn't implement support for Live Physical Time (LPT) as there are
> some concerns about the overheads and approach in the above
Do you plan to pick up LPT support? As there is demand of cross-frequency migration
(from older platform to newer platform).

I am not clear about the overheads and approach problem here, could you please
give some detail information? Maybe we can work together to solve these concerns. :-)

Thanks,
Keqian
> specification, and I expect an updated version of the specification to
> be released soon with just the stolen time parts.
>
> I previously posted a series including LPT (as well as stolen time):
> https://lore.kernel.org/kvmarm/20181212150226.38051-1-steven.price@arm.com/
>
> Patches 2, 5, 7 and 8 are cleanup patches and could be taken separately.
>
> Christoffer Dall (1):
> KVM: arm/arm64: Factor out hypercall handling from PSCI code
>
> Steven Price (8):
> KVM: arm64: Document PV-time interface
> KVM: arm64: Implement PV_FEATURES call
> KVM: arm64: Support stolen time reporting via shared structure
> KVM: Allow kvm_device_ops to be const
> KVM: arm64: Provide a PV_TIME device to user space
> arm/arm64: Provide a wrapper for SMCCC 1.1 calls
> arm/arm64: Make use of the SMCCC 1.1 wrapper
> arm64: Retrieve stolen time as paravirtualized guest
>
> Documentation/virtual/kvm/arm/pvtime.txt | 107 +++++++++++++
> arch/arm/kvm/Makefile | 2 +-
> arch/arm/kvm/handle_exit.c | 2 +-
> arch/arm/mm/proc-v7-bugs.c | 13 +-
> arch/arm64/include/asm/kvm_host.h | 13 +-
> arch/arm64/include/asm/kvm_mmu.h | 2 +
> arch/arm64/include/asm/pvclock-abi.h | 20 +++
> arch/arm64/include/uapi/asm/kvm.h | 6 +
> arch/arm64/kernel/Makefile | 1 +
> arch/arm64/kernel/cpu_errata.c | 80 ++++------
> arch/arm64/kernel/kvm.c | 155 ++++++++++++++++++
> arch/arm64/kvm/Kconfig | 1 +
> arch/arm64/kvm/Makefile | 2 +
> arch/arm64/kvm/handle_exit.c | 4 +-
> include/kvm/arm_hypercalls.h | 44 ++++++
> include/kvm/arm_psci.h | 2 +-
> include/linux/arm-smccc.h | 58 +++++++
> include/linux/cpuhotplug.h | 1 +
> include/linux/kvm_host.h | 4 +-
> include/linux/kvm_types.h | 2 +
> include/uapi/linux/kvm.h | 2 +
> virt/kvm/arm/arm.c | 18 +++
> virt/kvm/arm/hypercalls.c | 138 ++++++++++++++++
> virt/kvm/arm/mmu.c | 44 ++++++
> virt/kvm/arm/psci.c | 84 +---------
> virt/kvm/arm/pvtime.c | 190 +++++++++++++++++++++++
> virt/kvm/kvm_main.c | 6 +-
> 27 files changed, 848 insertions(+), 153 deletions(-)
> create mode 100644 Documentation/virtual/kvm/arm/pvtime.txt
> create mode 100644 arch/arm64/include/asm/pvclock-abi.h
> create mode 100644 arch/arm64/kernel/kvm.c
> create mode 100644 include/kvm/arm_hypercalls.h
> create mode 100644 virt/kvm/arm/hypercalls.c
> create mode 100644 virt/kvm/arm/pvtime.c
>