From: Will Deacon <will@kernel.org>
To: Gavin Shan <gshan@redhat.com>
Cc: Suzuki Poulose <suzuki.poulose@arm.com>,
Marc Zyngier <maz@kernel.org>,
Quentin Perret <qperret@google.com>,
James Morse <james.morse@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
kernel-team@android.com, kvmarm@lists.cs.columbia.edu,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v3 06/21] KVM: arm64: Add support for stage-2 map()/unmap() in generic page-table
Date: Thu, 3 Sep 2020 13:30:33 +0100 [thread overview]
Message-ID: <20200903123032.GB7412@willie-the-truck> (raw)
In-Reply-To: <4cb1fbc9-c20d-35f1-c0cc-da21c0562f0a@redhat.com>
On Thu, Sep 03, 2020 at 09:18:27PM +1000, Gavin Shan wrote:
> On 8/25/20 7:39 PM, Will Deacon wrote:
> > Add stage-2 map() and unmap() operations to the generic page-table code.
> >
> > Cc: Marc Zyngier <maz@kernel.org>
> > Cc: Quentin Perret <qperret@google.com>
> > Signed-off-by: Will Deacon <will@kernel.org>
> > ---
> > arch/arm64/include/asm/kvm_pgtable.h | 39 ++++
> > arch/arm64/kvm/hyp/pgtable.c | 262 +++++++++++++++++++++++++++
> > 2 files changed, 301 insertions(+)
[...]
> > +static int stage2_map_walk_table_post(u64 addr, u64 end, u32 level,
> > + kvm_pte_t *ptep,
> > + struct stage2_map_data *data)
> > +{
> > + int ret = 0;
> > +
> > + if (!data->anchor)
> > + return 0;
> > +
> > + free_page((unsigned long)kvm_pte_follow(*ptep));
> > + put_page(virt_to_page(ptep));
> > +
> > + if (data->anchor == ptep) {
> > + data->anchor = NULL;
> > + ret = stage2_map_walk_leaf(addr, end, level, ptep, data);
> > + }
> > +
> > + return ret;
> > +}
> > +
>
> As discussed in another thread, *ptep has been invalidated in stage2_map_walk_table_pre().
> It means *ptep has value of zero. The following call to free_page() is going to release
> the page frame corresponding to physical address 0x0. It's not correct. We might cache
> the original value of this page table entry so that it can be used here.
Ah, yes, I see what you mean. But it's odd that I haven't run into this
myself, so let me try to reproduce the issue first. Another solution is
to invalidate the table entry only by clearing the valid bit of the pte,
rather than zapping the entire thing to 0, which can be done later when we
clear the anchor.
Cheers,
Will
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next prev parent reply other threads:[~2020-09-03 12:31 UTC|newest]
Thread overview: 86+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-25 9:39 [PATCH v3 00/21] KVM: arm64: Rewrite page-table code and fault handling Will Deacon
2020-08-25 9:39 ` [PATCH v3 01/21] KVM: arm64: Remove kvm_mmu_free_memory_caches() Will Deacon
2020-08-25 9:39 ` [PATCH v3 02/21] KVM: arm64: Add stand-alone page-table walker infrastructure Will Deacon
2020-08-27 16:27 ` Alexandru Elisei
2020-08-28 15:43 ` Alexandru Elisei
2020-09-02 10:36 ` Will Deacon
2020-08-28 15:51 ` Alexandru Elisei
2020-09-02 10:49 ` Will Deacon
2020-09-02 6:31 ` Gavin Shan
2020-09-02 11:02 ` Will Deacon
2020-09-03 1:11 ` Gavin Shan
2020-08-25 9:39 ` [PATCH v3 03/21] KVM: arm64: Add support for creating kernel-agnostic stage-1 page tables Will Deacon
2020-08-28 15:35 ` Alexandru Elisei
2020-09-02 10:06 ` Will Deacon
2020-08-25 9:39 ` [PATCH v3 04/21] KVM: arm64: Use generic allocator for hyp stage-1 page-tables Will Deacon
2020-08-28 16:32 ` Alexandru Elisei
2020-09-02 11:35 ` Will Deacon
2020-09-02 14:48 ` Alexandru Elisei
2020-08-25 9:39 ` [PATCH v3 05/21] KVM: arm64: Add support for creating kernel-agnostic stage-2 page tables Will Deacon
2020-09-02 6:40 ` Gavin Shan
2020-09-02 11:30 ` Will Deacon
2020-08-25 9:39 ` [PATCH v3 06/21] KVM: arm64: Add support for stage-2 map()/unmap() in generic page-table Will Deacon
2020-09-01 16:24 ` Alexandru Elisei
2020-09-02 11:46 ` Will Deacon
2020-09-03 2:57 ` Gavin Shan
2020-09-03 5:27 ` Gavin Shan
2020-09-03 11:18 ` Gavin Shan
2020-09-03 12:30 ` Will Deacon [this message]
2020-09-03 16:15 ` Will Deacon
2020-09-04 0:47 ` Gavin Shan
2020-08-25 9:39 ` [PATCH v3 07/21] KVM: arm64: Convert kvm_phys_addr_ioremap() to generic page-table API Will Deacon
2020-09-01 17:08 ` Alexandru Elisei
2020-09-02 11:48 ` Will Deacon
2020-09-03 3:57 ` Gavin Shan
2020-08-25 9:39 ` [PATCH v3 08/21] KVM: arm64: Convert kvm_set_spte_hva() " Will Deacon
2020-09-02 15:37 ` Alexandru Elisei
2020-09-03 16:37 ` Will Deacon
2020-09-03 4:13 ` Gavin Shan
2020-08-25 9:39 ` [PATCH v3 09/21] KVM: arm64: Convert unmap_stage2_range() " Will Deacon
2020-09-02 16:23 ` Alexandru Elisei
2020-09-02 18:44 ` Alexandru Elisei
2020-09-03 17:57 ` Will Deacon
2020-09-08 13:07 ` Alexandru Elisei
2020-09-09 10:57 ` Alexandru Elisei
2020-09-03 4:19 ` Gavin Shan
2020-08-25 9:39 ` [PATCH v3 10/21] KVM: arm64: Add support for stage-2 page-aging in generic page-table Will Deacon
2020-09-03 4:33 ` Gavin Shan
2020-09-03 16:48 ` Will Deacon
2020-09-04 1:01 ` Gavin Shan
2020-08-25 9:39 ` [PATCH v3 11/21] KVM: arm64: Convert page-aging and access faults to generic page-table API Will Deacon
2020-09-03 4:37 ` Gavin Shan
2020-08-25 9:39 ` [PATCH v3 12/21] KVM: arm64: Add support for stage-2 write-protect in generic page-table Will Deacon
2020-09-03 4:47 ` Gavin Shan
2020-08-25 9:39 ` [PATCH v3 13/21] KVM: arm64: Convert write-protect operation to generic page-table API Will Deacon
2020-09-03 4:48 ` Gavin Shan
2020-08-25 9:39 ` [PATCH v3 14/21] KVM: arm64: Add support for stage-2 cache flushing in generic page-table Will Deacon
2020-09-03 4:51 ` Gavin Shan
2020-08-25 9:39 ` [PATCH v3 15/21] KVM: arm64: Convert memslot cache-flushing code to generic page-table API Will Deacon
2020-09-03 4:52 ` Gavin Shan
2020-08-25 9:39 ` [PATCH v3 16/21] KVM: arm64: Add support for relaxing stage-2 perms in generic page-table code Will Deacon
2020-09-03 4:55 ` Gavin Shan
2020-08-25 9:39 ` [PATCH v3 17/21] KVM: arm64: Convert user_mem_abort() to generic page-table API Will Deacon
2020-09-03 6:05 ` Gavin Shan
2020-08-25 9:39 ` [PATCH v3 18/21] KVM: arm64: Check the pgt instead of the pgd when modifying page-table Will Deacon
2020-09-03 5:00 ` Gavin Shan
2020-08-25 9:39 ` [PATCH v3 19/21] KVM: arm64: Remove unused page-table code Will Deacon
2020-09-03 6:02 ` Gavin Shan
2020-08-25 9:39 ` [PATCH v3 20/21] KVM: arm64: Remove unused 'pgd' field from 'struct kvm_s2_mmu' Will Deacon
2020-09-03 5:07 ` Gavin Shan
2020-09-03 16:50 ` Will Deacon
2020-09-04 0:59 ` Gavin Shan
2020-09-04 10:02 ` Marc Zyngier
2020-08-25 9:39 ` [PATCH v3 21/21] KVM: arm64: Don't constrain maximum IPA size based on host configuration Will Deacon
2020-09-03 5:09 ` Gavin Shan
2020-08-27 16:26 ` [PATCH v3 00/21] KVM: arm64: Rewrite page-table code and fault handling Alexandru Elisei
2020-09-01 16:15 ` Will Deacon
2020-09-03 7:34 ` Gavin Shan
2020-09-03 11:13 ` Gavin Shan
2020-09-03 11:48 ` Gavin Shan
2020-09-03 12:16 ` Will Deacon
2020-09-04 0:51 ` Gavin Shan
2020-09-04 10:07 ` Marc Zyngier
2020-09-05 3:56 ` Gavin Shan
2020-09-05 9:33 ` Marc Zyngier
2020-09-07 9:27 ` Will Deacon
2020-09-03 18:52 ` Will Deacon
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