Re: [PATCH v2 00/23] MIPS: KVM: Fixes and guest timer rewrite

Paolo Bonzini
2014-05-30T11:07:18Z

Il 29/05/2014 11:16, James Hogan ha scritto:
> Here are a range of MIPS KVM T&E fixes, preferably for v3.16 but I know
> it's probably a bit late now. Changes are pretty minimal though since
> v1 so please consider. They can also be found on my kvm_mips_queue
> branch (and the kvm_mips_timer_v2 tag) here:
> git://git.kernel.org/pub/scm/linux/kernel/git/jhogan/kvm-mips.git
>
> They originally served to allow it to work better on Ingenic XBurst
> cores which have some peculiarities which break non-portable assumptions
> in the MIPS KVM implementation (patches 1-4, 13).
>
> Fixing guest CP0_Count emulation to work without a running host
> CP0_Count (patch 13) however required a rewrite of the timer emulation
> code to use the kernel monotonic time instead, which needed doing anyway
> since basing it directly off the host CP0_Count was broken. Various bugs
> were fixed in the process (patches 10-12) and improvements made thanks to
> valuable feedback from Paolo Bonzini for the last QEMU MIPS/KVM patchset
> (patches 5-7, 15-16).
>
> Finally there are some misc cleanups which I did along the way (patches
> 17-23).
>
> Only the first patch (fixes MIPS KVM with 4K pages) is marked for
> stable. For KVM to work on XBurst it needs the timer rework which is a
> fairly complex change, so there's little point marking any of the XBurst
> specific changes for stable.
>
> All feedback welcome!
>
> Patches 1-4:
> Fix KVM/MIPS with 4K pages, missing RDHWR SYNCI (XBurst),
> unmoving CP0_Random (XBurst).
> Patches 5-9:
> Add EPC, Count, Compare, UserLocal, HWREna guest CP0 registers
> to KVM register ioctl interface.
> Patches 10-12:
> Fix a few potential races relating to timers.
> Patches 13-14:
> Rewrite guest timer emulation to use ktime_get().
> Patches 15-16:
> Add KVM virtual registers for controlling guest timer, including
> master timer disable, and timer frequency.
> Patches 17-23:
> Cleanups.
>
> Changes in v2 (tag:kvm_mips_timer_v2):
> Patchset:
> - Drop patch 4 "MIPS: KVM: Fix CP0_EBASE KVM register id" (David
> Daney).
> - Drop patch 14 "MIPS: KVM: Add nanosecond count bias KVM register".
> The COUNT_CTL and COUNT_RESUME API is clean and sufficient.
> - Add missing access to UserLocal and HWREna guest CP0 registers
> (patches 15 and 16).
> - Add export of local_flush_icache_range (patch 2).
> Patch 12 MIPS: KVM: Migrate hrtimer to follow VCPU
> - Move kvm_mips_migrate_count() into kvm_tlb.c to fix a link error when
> KVM is built as a module, since kvm_tlb.c is built statically and
> cannot reference symbols in kvm_mips_emul.c.
> Patch 15 MIPS: KVM: Add master disable count interface
> - Make KVM_REG_MIPS_COUNT_RESUME writable too so that userland can
> control timer using master DC and without bias register. New values
> are rejected if they refer to a monotonic time in the future.
> - Expand on description of KVM_REG_MIPS_COUNT_RESUME about the effects
> of the register and that it can be written.
>
> v1 (tag:kvm_mips_timer_v1):
> see http://marc.info/?l=kvm&m=139843936102657&w=2
>
> James Hogan (23):
> MIPS: KVM: Allocate at least 16KB for exception handlers
> MIPS: Export local_flush_icache_range for KVM
> MIPS: KVM: Use local_flush_icache_range to fix RI on XBurst
> MIPS: KVM: Use tlb_write_random
> MIPS: KVM: Add CP0_EPC KVM register access
> MIPS: KVM: Move KVM_{GET,SET}_ONE_REG definitions into kvm_host.h
> MIPS: KVM: Add CP0_Count/Compare KVM register access
> MIPS: KVM: Add CP0_UserLocal KVM register access
> MIPS: KVM: Add CP0_HWREna KVM register access
> MIPS: KVM: Deliver guest interrupts after local_irq_disable()
> MIPS: KVM: Fix timer race modifying guest CP0_Cause
> MIPS: KVM: Migrate hrtimer to follow VCPU
> MIPS: KVM: Rewrite count/compare timer emulation
> MIPS: KVM: Override guest kernel timer frequency directly
> MIPS: KVM: Add master disable count interface
> MIPS: KVM: Add count frequency KVM register
> MIPS: KVM: Make kvm_mips_comparecount_{func,wakeup} static
> MIPS: KVM: Whitespace fixes in kvm_mips_callbacks
> MIPS: KVM: Fix kvm_debug bit-rottage
> MIPS: KVM: Remove ifdef DEBUG around kvm_debug
> MIPS: KVM: Quieten kvm_info() logging
> MIPS: KVM: Remove redundant NULL checks before kfree()
> MIPS: KVM: Remove redundant semicolon
>
> arch/mips/Kconfig | 12 +-
> arch/mips/include/asm/kvm_host.h | 183 ++++++++++---
> arch/mips/include/uapi/asm/kvm.h | 35 +++
> arch/mips/kvm/kvm_locore.S | 32 ---
> arch/mips/kvm/kvm_mips.c | 140 +++++-----
> arch/mips/kvm/kvm_mips_dyntrans.c | 15 +-
> arch/mips/kvm/kvm_mips_emul.c | 557 ++++++++++++++++++++++++++++++++++++--
> arch/mips/kvm/kvm_tlb.c | 77 +++---
> arch/mips/kvm/kvm_trap_emul.c | 86 +++++-
> arch/mips/mm/cache.c | 1 +
> arch/mips/mti-malta/malta-time.c | 14 +-
> 11 files changed, 920 insertions(+), 232 deletions(-)
>
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Cc: Gleb Natapov <gleb@kernel.org>
> Cc: kvm@vger.kernel.org
> Cc: Ralf Baechle <ralf@linux-mips.org>
> Cc: linux-mips@linux-mips.org
> Cc: David Daney <david.daney@cavium.com>
> Cc: Andreas Herrmann <andreas.herrmann@caviumnetworks.com>
> Cc: Sanjay Lal <sanjayl@kymasys.com>
>

Applied, thanks. I hope you'll get the QEMU patches ready in time for
2.1! :)

Paolo