linux-kernel - Re: [PATCH v4 1/2] KVM: arm64: Move CMOs from user_mem

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Date:   Fri, 09 Apr 2021 10:00:33 +0100
From:   Marc Zyngier <maz@...nel.org>
To:     Quentin Perret <qperret@...gle.com>
Cc:     Yanan Wang <wangyanan55@...wei.com>, Will Deacon <will@...nel.org>,
        Alexandru Elisei <alexandru.elisei@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        kvmarm@...ts.cs.columbia.edu, linux-arm-kernel@...ts.infradead.org,
        kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        James Morse <james.morse@....com>,
        Julien Thierry <julien.thierry.kdev@...il.com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Gavin Shan <gshan@...hat.com>, wanghaibin.wang@...wei.com,
        zhukeqian1@...wei.com, yuzenghui@...wei.com
Subject: Re: [PATCH v4 1/2] KVM: arm64: Move CMOs from user_mem_abort to the fault handlers

On Fri, 09 Apr 2021 09:08:11 +0100,
Quentin Perret <qperret@...gle.com> wrote:
> 
> Hi Yanan,
> 
> On Friday 09 Apr 2021 at 11:36:51 (+0800), Yanan Wang wrote:
> > diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
> > +static void stage2_invalidate_icache(void *addr, u64 size)
> > +{
> > +	if (icache_is_aliasing()) {
> > +		/* Flush any kind of VIPT icache */
> > +		__flush_icache_all();
> > +	} else if (is_kernel_in_hyp_mode() || !icache_is_vpipt()) {
> > +		/* PIPT or VPIPT at EL2 */
> > +		invalidate_icache_range((unsigned long)addr,
> > +					(unsigned long)addr + size);
> > +	}
> > +}
> > +
> 
> I would recommend to try and rebase this patch on kvmarm/next because
> we've made a few changes in pgtable.c recently. It is now linked into
> the EL2 NVHE code which means there are constraints on what can be used
> from there -- you'll need a bit of extra work to make some of these
> functions available to EL2.

That's an interesting point.

I wonder whether we are missing something on the i-side for VPITP +
host stage-2 due to switching HCR_EL2.VM. We haven't changed the VMID
(still 0), but I can't bring myself to be sure it doesn't affect the
icache in this case...

	M.

-- 
Without deviation from the norm, progress is not possible.