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From: "Philippe Mathieu-Daudé" <f4bug@amsat.org>
To: Paolo Bonzini <pbonzini@redhat.com>,
	Paul Burton <paulburton@kernel.org>,
	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 20:02:34 +0100
Message-ID: <26c57acc-cec4-9f61-a98e-25c49d5f43e6@amsat.org> (raw)
In-Reply-To: <66e0a38c-a7f5-dcd1-d06b-b317588fad7a@redhat.com>

On 2/12/20 5:40 PM, Paolo Bonzini wrote:
> On 12/02/20 17:30, Paul Burton wrote:
>> 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...
> 
> Ok, I'll try to whip out a patch that handles __PAGETABLE_PUD_FOLDED.
> On the other hand this makes me worry about how much KVM is being tested
> by people that care about MIPS (even just compile-tested).

FYI last time James confirmed he tested QEMU was in 2017:
https://www.mail-archive.com/qemu-devel@nongnu.org/msg477133.html

At the end of 2019 he orphaned the QEMU part:
https://www.mail-archive.com/qemu-devel@nongnu.org/msg667240.html
and dropped the kernel maintainance:
https://git.kernel.org/pub/scm/linux/kernel/git/mips/linux.git/commit/?id=9c48c48cd499

  reply index

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-07 22:35 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
2020-02-12 16:40     ` Paolo Bonzini
2020-02-12 19:02       ` Philippe Mathieu-Daudé [this message]
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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