linux-kernel - [PATCH RFC 0/4] KVM: MIPS: Provide arch-specific kvm_flush_remote

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Date:   Fri,  7 Feb 2020 17:35:16 -0500
From:   Peter Xu <peterx@...hat.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     Sean Christopherson <sean.j.christopherson@...el.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        linux-mips@...r.kernel.org, peterx@...hat.com,
        Vitaly Kuznetsov <vkuznets@...hat.com>
Subject: [PATCH RFC 0/4] KVM: MIPS: Provide arch-specific kvm_flush_remote_tlbs()

[This series is RFC because I don't have MIPS to compile and test]

kvm_flush_remote_tlbs() can be arch-specific, by either:

- Completely replace kvm_flush_remote_tlbs(), like ARM, who is the
  only user of CONFIG_HAVE_KVM_ARCH_TLB_FLUSH_ALL so far

- Doing something extra before kvm_flush_remote_tlbs(), like MIPS VZ
  support, however still wants to have the common tlb flush to be part
  of the process.  Could refer to kvm_vz_flush_shadow_all().  Then in
  MIPS it's awkward to flush remote TLBs: we'll need to call the mips
  hooks.

It's awkward to have different ways to specialize this procedure,
especially MIPS cannot use the genenal interface which is quite a
pity.  It's good to make it a common interface.

This patch series removes the 2nd MIPS usage above, and let it also
use the common kvm_flush_remote_tlbs() interface.  It should be
suggested that we always keep kvm_flush_remote_tlbs() be a common
entrance for tlb flushing on all archs.

This idea comes from the reading of Sean's patchset on dynamic memslot
allocation, where a new dirty log specific hook is added for flushing
TLBs only for the MIPS code [1].  With this patchset, logically the
new hook in that patch can be dropped so we can directly use
kvm_flush_remote_tlbs().

TODO: We can even extend another common interface for ranged TLB, but
let's see how we think about this series first.

Any comment is welcomed, thanks.

Peter Xu (4):
  KVM: Provide kvm_flush_remote_tlbs_common()
  KVM: MIPS: Drop flush_shadow_memslot() callback
  KVM: MIPS: Replace all the kvm_flush_remote_tlbs() references
  KVM: MIPS: Define arch-specific kvm_flush_remote_tlbs()

 arch/mips/include/asm/kvm_host.h |  7 -------
 arch/mips/kvm/Kconfig            |  1 +
 arch/mips/kvm/mips.c             | 22 ++++++++++------------
 arch/mips/kvm/trap_emul.c        | 15 +--------------
 arch/mips/kvm/vz.c               | 14 ++------------
 include/linux/kvm_host.h         |  1 +
 virt/kvm/kvm_main.c              | 10 ++++++++--
 7 files changed, 23 insertions(+), 47 deletions(-)

-- 
2.24.1