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From: Paul Burton <paulburton@kernel.org>
To: Paolo Bonzini <pbonzini@redhat.com>, Mike Rapoport <rppt@linux.ibm.com>
Cc: Peter Xu <peterx@redhat.com>,
	linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
	Sean Christopherson <sean.j.christopherson@intel.com>,
	linux-mips@vger.kernel.org,
	Vitaly Kuznetsov <vkuznets@redhat.com>
Subject: Re: [PATCH RFC 0/4] KVM: MIPS: Provide arch-specific kvm_flush_remote_tlbs()
Date: Wed, 12 Feb 2020 08:30:04 -0800	[thread overview]
Message-ID: <20200212163004.cpd33ux4zslfc3es@lantea.localdomain> (raw)
In-Reply-To: <44ba59d6-39a5-4221-1ae6-41e5a305d316@redhat.com>

Hi Paolo,

On Wed, Feb 12, 2020 at 01:25:30PM +0100, Paolo Bonzini wrote:
> 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?

I'm no expert on this bit of code, but I'm pretty sure the systems
KVM/VZ has been used on the most internally had PGTABLE_LEVEL=3.

I suspect this is actually a regression from commit 31168f033e37 ("mips:
drop __pXd_offset() macros that duplicate pXd_index() ones"). Whilst
that commit is correct that pud_index() & __pud_offset() are the same
when pud_index() is actually provided, it doesn't take into account the
__PAGETABLE_PUD_FOLDED case. There __pud_offset() was available but
would always evaluate to zero, whereas pud_index() isn't defined...

Thanks,
    Paul

  reply	other threads:[~2020-02-12 16:30 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-07 22:35 [PATCH RFC 0/4] KVM: MIPS: Provide arch-specific kvm_flush_remote_tlbs() Peter Xu
2020-02-07 22:35 ` [PATCH RFC 1/4] KVM: Provide kvm_flush_remote_tlbs_common() Peter Xu
2020-02-12 13:33   ` Paolo Bonzini
2020-02-07 22:35 ` [PATCH RFC 2/4] KVM: MIPS: Drop flush_shadow_memslot() callback Peter Xu
2020-02-07 22:35 ` [PATCH RFC 3/4] KVM: MIPS: Replace all the kvm_flush_remote_tlbs() references Peter Xu
2020-02-07 22:35 ` [PATCH RFC 4/4] KVM: MIPS: Define arch-specific kvm_flush_remote_tlbs() Peter Xu
2020-03-18  3:03   ` maobibo
2020-03-18 15:28     ` Peter Xu
2020-03-19  2:21       ` maobibo
2020-02-07 23:00 ` [PATCH RFC 0/4] KVM: MIPS: Provide " Peter Xu
2020-02-12 12:25 ` Paolo Bonzini
2020-02-12 16:30   ` Paul Burton [this message]
2020-02-12 16:40     ` Paolo Bonzini
2020-02-12 19:02       ` Philippe Mathieu-Daudé
2020-03-11 18:32   ` Peter Xu
2020-03-17 13:33     ` Paolo Bonzini
2020-03-17 14:18       ` Peter Xu

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