From: Will Deacon <will@kernel.org>
To: Gavin Shan <gshan@redhat.com>
Cc: kernel-team@android.com, 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>,
Alexandru Elisei <alexandru.elisei@arm.com>,
kvmarm@lists.cs.columbia.edu,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v4 02/21] KVM: arm64: Add stand-alone page-table walker infrastructure
Date: Thu, 10 Sep 2020 11:57:27 +0100 [thread overview]
Message-ID: <20200910105727.GC17887@willie-the-truck> (raw)
In-Reply-To: <56510d79-ce08-c058-03f8-10b1a37d05b0@redhat.com>
On Tue, Sep 08, 2020 at 10:03:30AM +1000, Gavin Shan wrote:
> On 9/8/20 1:23 AM, Will Deacon wrote:
> > The KVM page-table code is intricately tied into the kernel page-table
> > code and re-uses the pte/pmd/pud/p4d/pgd macros directly in an attempt
> > to reduce code duplication. Unfortunately, the reality is that there is
> > an awful lot of code required to make this work, and at the end of the
> > day you're limited to creating page-tables with the same configuration
> > as the host kernel. Furthermore, lifting the page-table code to run
> > directly at EL2 on a non-VHE system (as we plan to to do in future
> > patches) is practically impossible due to the number of dependencies it
> > has on the core kernel.
> >
> > Introduce a framework for walking Armv8 page-tables configured
> > independently from the host kernel.
> >
> > Cc: Marc Zyngier <maz@kernel.org>
> > Cc: Quentin Perret <qperret@google.com>
> > Signed-off-by: Will Deacon <will@kernel.org>
> > ---
>
> It looks good to me. However, If you get a chance to respin, I guess
> it would be nice to add some comments about kvm_block_mapping_supported().
> More details are provoided below.
>
> Reviewed-by: Gavin Shan <gshan@redhat.com>
[...]
> > +static bool kvm_block_mapping_supported(u64 addr, u64 end, u64 phys, u32 level)
> > +{
> > + u64 granule = kvm_granule_size(level);
> > +
> > + /*
> > + * Reject invalid block mappings and don't bother with 4TB mappings for
> > + * 52-bit PAs.
> > + */
> > + if (level == 0 || (PAGE_SIZE != SZ_4K && level == 1))
> > + return false;
> > +
> > + if (granule > (end - addr))
> > + return false;
> > +
> > + return IS_ALIGNED(addr, granule) && IS_ALIGNED(phys, granule);
> > +}
> > +
>
> If you get a chance to respin, it would be nice to have more comments to
> explain why 4TB block mapping is rejected here. I guess it depends on the
> fact: hugeTLB/THP doesn't support such kind of huge block mapping yet?
It's just because I'm lazy, really :) We don't know if we're using 52-bit
PAs here, and I couldn't be bothered to propagate that information given
that this doesn't seem like something anybody will be using at the moment.
Will
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next prev parent reply other threads:[~2020-09-10 10:58 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-07 15:23 [PATCH v4 00/21] KVM: arm64: Rewrite page-table code and fault handling Will Deacon
2020-09-07 15:23 ` [PATCH v4 01/21] KVM: arm64: Remove kvm_mmu_free_memory_caches() Will Deacon
2020-09-07 15:23 ` [PATCH v4 02/21] KVM: arm64: Add stand-alone page-table walker infrastructure Will Deacon
2020-09-08 0:03 ` Gavin Shan
2020-09-10 10:57 ` Will Deacon [this message]
2020-09-09 15:29 ` Alexandru Elisei
2020-09-10 12:37 ` Will Deacon
2020-09-10 14:21 ` Andrew Scull
2020-09-11 10:15 ` Will Deacon
2020-09-11 11:22 ` Andrew Scull
2020-09-07 15:23 ` [PATCH v4 03/21] KVM: arm64: Add support for creating kernel-agnostic stage-1 page tables Will Deacon
2020-09-08 1:09 ` Gavin Shan
2020-09-07 15:23 ` [PATCH v4 04/21] KVM: arm64: Use generic allocator for hyp stage-1 page-tables Will Deacon
2020-09-08 1:03 ` Gavin Shan
2020-09-07 15:23 ` [PATCH v4 05/21] KVM: arm64: Add support for creating kernel-agnostic stage-2 page tables Will Deacon
2020-09-07 15:23 ` [PATCH v4 06/21] KVM: arm64: Add support for stage-2 map()/unmap() in generic page-table Will Deacon
2020-09-10 11:20 ` Alexandru Elisei
2020-09-10 12:34 ` Will Deacon
2020-09-10 13:55 ` Alexandru Elisei
2020-09-07 15:23 ` [PATCH v4 07/21] KVM: arm64: Convert kvm_phys_addr_ioremap() to generic page-table API Will Deacon
2020-09-07 15:23 ` [PATCH v4 08/21] KVM: arm64: Convert kvm_set_spte_hva() " Will Deacon
2020-09-07 15:23 ` [PATCH v4 09/21] KVM: arm64: Convert unmap_stage2_range() " Will Deacon
2020-09-07 15:23 ` [PATCH v4 10/21] KVM: arm64: Add support for stage-2 page-aging in generic page-table Will Deacon
2020-09-08 15:30 ` Alexandru Elisei
2020-09-10 12:42 ` Will Deacon
2020-09-07 15:23 ` [PATCH v4 11/21] KVM: arm64: Convert page-aging and access faults to generic page-table API Will Deacon
2020-09-08 15:39 ` Alexandru Elisei
2020-09-07 15:23 ` [PATCH v4 12/21] KVM: arm64: Add support for stage-2 write-protect in generic page-table Will Deacon
2020-09-07 15:23 ` [PATCH v4 13/21] KVM: arm64: Convert write-protect operation to generic page-table API Will Deacon
2020-09-07 15:23 ` [PATCH v4 14/21] KVM: arm64: Add support for stage-2 cache flushing in generic page-table Will Deacon
2020-09-07 15:23 ` [PATCH v4 15/21] KVM: arm64: Convert memslot cache-flushing code to generic page-table API Will Deacon
2020-09-07 15:23 ` [PATCH v4 16/21] KVM: arm64: Add support for relaxing stage-2 perms in generic page-table code Will Deacon
2020-09-08 16:37 ` Alexandru Elisei
2020-09-07 15:23 ` [PATCH v4 17/21] KVM: arm64: Convert user_mem_abort() to generic page-table API Will Deacon
2020-09-09 14:20 ` Alexandru Elisei
2020-09-09 17:12 ` Marc Zyngier
2020-09-10 10:51 ` Will Deacon
2020-09-10 10:58 ` Marc Zyngier
2020-09-10 13:10 ` Alexandru Elisei
2020-09-10 13:20 ` Alexandru Elisei
2020-09-07 15:23 ` [PATCH v4 18/21] KVM: arm64: Check the pgt instead of the pgd when modifying page-table Will Deacon
2020-09-07 15:23 ` [PATCH v4 19/21] KVM: arm64: Remove unused page-table code Will Deacon
2020-09-08 10:33 ` Marc Zyngier
2020-09-10 10:54 ` Will Deacon
2020-09-07 15:23 ` [PATCH v4 20/21] KVM: arm64: Remove unused 'pgd' field from 'struct kvm_s2_mmu' Will Deacon
2020-09-07 15:23 ` [PATCH v4 21/21] KVM: arm64: Don't constrain maximum IPA size based on host configuration Will Deacon
2020-09-09 14:53 ` Alexandru Elisei
2020-09-07 17:16 ` [PATCH v4 00/21] KVM: arm64: Rewrite page-table code and fault handling Marc Zyngier
2020-09-07 17:31 ` Will Deacon
2020-09-10 4:06 ` Gavin Shan
2020-09-10 4:11 ` Gavin Shan
2020-09-10 10:58 ` Will Deacon
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