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SubjectRe: [PATCH RFC 0/4] KVM: MIPS: Provide arch-specific kvm_flush_remote_tlbs()
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On 07/02/20 23:35, Peter Xu wrote:
> [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(-)
>

Compile-tested and queued.

MIPS folks, I see that arch/mips/kvm/mmu.c uses pud_index, so it's not
clear to me if it's meant to only work if CONFIG_PGTABLE_LEVELS=4 or
it's just bit rot. Should I add a "depends on PGTABLE_LEVEL=4" to
arch/mips/Kconfig?

Paolo

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