From: Will Deacon <will@kernel.org>
To: Marc Zyngier <maz@kernel.org>
Cc: jiangkunkun@huawei.com, Gavin Shan <gshan@redhat.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
wangjingyi11@huawei.com, Quentin Perret <qperret@google.com>,
lushenming@huawei.com, linux-kernel@vger.kernel.org,
"wangyanan \(Y\)" <wangyanan55@huawei.com>,
yezengruan@huawei.com, James Morse <james.morse@arm.com>,
linux-arm-kernel@lists.infradead.org, yuzenghui@huawei.com,
wanghaibin.wang@huawei.com, zhukeqian1@huawei.com,
Julien Thierry <julien.thierry.kdev@gmail.com>
Subject: Re: [RFC PATCH 2/3] KVM: arm64: Fix handling of merging tables into a block entry
Date: Tue, 1 Dec 2020 14:23:25 +0000 [thread overview]
Message-ID: <20201201142324.GD26973@willie-the-truck> (raw)
In-Reply-To: <03ab1bdd8459831ad05993807e39e5bd@kernel.org>
On Tue, Dec 01, 2020 at 02:05:03PM +0000, Marc Zyngier wrote:
> On 2020-12-01 13:46, Will Deacon wrote:
> > diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
> > index 0271b4a3b9fe..12526d8c7ae4 100644
> > --- a/arch/arm64/kvm/hyp/pgtable.c
> > +++ b/arch/arm64/kvm/hyp/pgtable.c
> > @@ -493,7 +493,7 @@ static int stage2_map_walk_table_pre(u64 addr, u64
> > end, u32 level,
> > return 0;
> >
> > kvm_set_invalid_pte(ptep);
> > - kvm_call_hyp(__kvm_tlb_flush_vmid_ipa, data->mmu, addr, 0);
> > + /* TLB invalidation is deferred until the _post handler */
> > data->anchor = ptep;
> > return 0;
> > }
> > @@ -547,11 +547,21 @@ static int stage2_map_walk_table_post(u64 addr,
> > u64 end, u32 level,
> > struct stage2_map_data *data)
> > {
> > int ret = 0;
> > + kvm_pte_t pte = *ptep;
> >
> > if (!data->anchor)
> > return 0;
> >
> > - free_page((unsigned long)kvm_pte_follow(*ptep));
> > + kvm_set_invalid_pte(ptep);
> > +
> > + /*
> > + * Invalidate the whole stage-2, as we may have numerous leaf
> > + * entries below us which would otherwise need invalidating
> > + * individually.
> > + */
> > + kvm_call_hyp(__kvm_tlb_flush_vmid, data->mmu);
>
> That's a big hammer, and we so far have been pretty careful not to
> over-invalidate. Is the block-replacing-table *without* an unmap
> in between the only case where this triggers?
Yes, this only happens in that case. The alternative would be to issue
invalidations for every single entry we unmap, which I can implement if
you prefer, but it felt worse to me given that by-IPA invalidation
isn't really great either).
Will
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next prev parent reply other threads:[~2020-12-01 14:24 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-30 12:18 [RFC PATCH 0/3] Fix several bugs in KVM stage 2 translation Yanan Wang
2020-11-30 12:18 ` [RFC PATCH 1/3] KVM: arm64: Fix possible memory leak in kvm stage2 Yanan Wang
2020-11-30 13:21 ` Will Deacon
2020-12-01 7:21 ` wangyanan (Y)
2020-12-01 14:16 ` Will Deacon
2020-12-01 17:19 ` wangyanan (Y)
2020-12-01 18:15 ` Will Deacon
2020-12-01 20:08 ` wangyanan (Y)
2020-11-30 12:18 ` [RFC PATCH 2/3] KVM: arm64: Fix handling of merging tables into a block entry Yanan Wang
2020-11-30 13:34 ` Will Deacon
2020-11-30 15:24 ` wangyanan (Y)
2020-11-30 16:01 ` Will Deacon
2020-12-01 2:30 ` wangyanan (Y)
2020-12-01 13:46 ` Will Deacon
2020-12-01 14:05 ` Marc Zyngier
2020-12-01 14:23 ` Will Deacon [this message]
2020-12-01 14:32 ` Marc Zyngier
2020-12-01 14:11 ` wangyanan (Y)
2020-12-01 14:35 ` Marc Zyngier
2020-12-01 17:20 ` wangyanan (Y)
2020-12-01 18:17 ` Will Deacon
2020-11-30 12:18 ` [RFC PATCH 3/3] KVM: arm64: Add usage of stage 2 fault lookup level in user_mem_abort() Yanan Wang
2020-11-30 13:49 ` Will Deacon
2020-12-01 6:04 ` wangyanan (Y)
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