From: Will Deacon <will@kernel.org>
To: Quentin Perret <qperret@google.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
Marc Zyngier <maz@kernel.org>, James Morse <james.morse@arm.com>,
Julien Thierry <julien.thierry.kdev@gmail.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Rob Herring <robh+dt@kernel.org>,
Frank Rowand <frowand.list@gmail.com>,
devicetree@vger.kernel.org, android-kvm@google.com,
linux-kernel@vger.kernel.org, kernel-team@android.com,
kvmarm@lists.cs.columbia.edu,
linux-arm-kernel@lists.infradead.org,
Fuad Tabba <tabba@google.com>,
Mark Rutland <mark.rutland@arm.com>,
David Brazdil <dbrazdil@google.com>
Subject: Re: [RFC PATCH v2 16/26] KVM: arm64: Prepare Hyp memory protection
Date: Fri, 5 Feb 2021 17:56:02 +0000 [thread overview]
Message-ID: <20210205175602.GG22665@willie-the-truck> (raw)
In-Reply-To: <YBvQrHdbiNTSLQq6@google.com>
On Thu, Feb 04, 2021 at 10:47:08AM +0000, Quentin Perret wrote:
> On Wednesday 03 Feb 2021 at 14:37:10 (+0000), Will Deacon wrote:
> > On Fri, Jan 08, 2021 at 12:15:14PM +0000, Quentin Perret wrote:
> > > +static inline unsigned long __hyp_pgtable_max_pages(unsigned long nr_pages)
> > > +{
> > > + unsigned long total = 0, i;
> > > +
> > > + /* Provision the worst case scenario with 4 levels of page-table */
> > > + for (i = 0; i < 4; i++) {
> >
> > Looks like you want KVM_PGTABLE_MAX_LEVELS, so maybe move that into a
> > header?
>
> Will do.
>
> >
> > > + nr_pages = DIV_ROUND_UP(nr_pages, PTRS_PER_PTE);
> > > + total += nr_pages;
> > > + }
> >
> > ... that said, I'm not sure this needs to iterate at all. What exactly are
> > you trying to compute?
>
> I'm trying to figure out how many pages I will need to construct a
> page-table covering nr_pages contiguous pages. The first iteration tells
> me how many level 0 pages I need to cover nr_pages, the second iteration
> how many level 1 pages I need to cover the level 0 pages, and so on...
Ah, you iterate from leaves back to the root. Got it, thanks.
> I might be doing this naively though. Got a better idea?
I thought I did, but I ended up with something based on a geometric series
and it looks terrible to code-up in C without, err, iterating like you do.
So yeah, ignore me :)
> > > +
> > > + return total;
> > > +}
> > > +
> > > +static inline unsigned long hyp_s1_pgtable_size(void)
> > > +{
> > > + struct hyp_memblock_region *reg;
> > > + unsigned long nr_pages, res = 0;
> > > + int i;
> > > +
> > > + if (kvm_nvhe_sym(hyp_memblock_nr) <= 0)
> > > + return 0;
> >
> > It's a bit grotty having this be signed. Why do we need to encode the error
> > case differently from the 0 case?
>
> Here specifically we don't, but it is needed in early_init_dt_add_memory_hyp()
> to distinguish the overflow case from the first memblock being added.
Fair enough, but if you figure out a way for hyp_memblock_nr to be unsigned,
I think that would be preferable.
Will
next prev parent reply other threads:[~2021-02-05 18:00 UTC|newest]
Thread overview: 97+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-08 12:14 [RFC PATCH v2 00/26] KVM/arm64: A stage 2 for the host Quentin Perret
2021-01-08 12:14 ` [RFC PATCH v2 01/26] arm64: lib: Annotate {clear,copy}_page() as position-independent Quentin Perret
2021-01-08 12:15 ` [RFC PATCH v2 02/26] KVM: arm64: Link position-independent string routines into .hyp.text Quentin Perret
2021-01-08 12:15 ` [RFC PATCH v2 03/26] arm64: kvm: Add standalone ticket spinlock implementation for use at hyp Quentin Perret
2021-02-01 17:28 ` Will Deacon
2021-02-01 17:40 ` Quentin Perret
2021-01-08 12:15 ` [RFC PATCH v2 04/26] KVM: arm64: Initialize kvm_nvhe_init_params early Quentin Perret
2021-02-01 17:41 ` Will Deacon
2021-01-08 12:15 ` [RFC PATCH v2 05/26] KVM: arm64: Avoid free_page() in page-table allocator Quentin Perret
2021-02-01 17:46 ` Will Deacon
2021-01-08 12:15 ` [RFC PATCH v2 06/26] KVM: arm64: Factor memory allocation out of pgtable.c Quentin Perret
2021-02-01 18:16 ` Will Deacon
2021-02-01 18:32 ` Quentin Perret
2021-02-01 18:39 ` Will Deacon
2021-01-08 12:15 ` [RFC PATCH v2 07/26] KVM: arm64: Introduce a BSS section for use at Hyp Quentin Perret
2021-02-01 18:32 ` Will Deacon
2021-01-08 12:15 ` [RFC PATCH v2 08/26] KVM: arm64: Make kvm_call_hyp() a function call " Quentin Perret
2021-02-01 18:41 ` Will Deacon
2021-01-08 12:15 ` [RFC PATCH v2 09/26] KVM: arm64: Allow using kvm_nvhe_sym() in hyp code Quentin Perret
2021-02-01 18:43 ` Will Deacon
2021-01-08 12:15 ` [RFC PATCH v2 10/26] KVM: arm64: Introduce an early Hyp page allocator Quentin Perret
2021-02-01 19:00 ` Will Deacon
2021-02-02 9:44 ` Quentin Perret
2021-01-08 12:15 ` [RFC PATCH v2 11/26] KVM: arm64: Stub CONFIG_DEBUG_LIST at Hyp Quentin Perret
2021-02-01 19:06 ` Will Deacon
2021-02-02 9:57 ` Quentin Perret
2021-02-02 10:00 ` Will Deacon
2021-02-02 10:14 ` Quentin Perret
2021-01-08 12:15 ` [RFC PATCH v2 12/26] KVM: arm64: Introduce a Hyp buddy page allocator Quentin Perret
2021-02-02 18:13 ` Will Deacon
2021-02-03 18:33 ` Quentin Perret
2021-02-04 14:31 ` Will Deacon
2021-02-04 14:52 ` Quentin Perret
2021-02-04 17:48 ` Will Deacon
2021-02-04 18:01 ` Quentin Perret
2021-02-04 18:13 ` Will Deacon
2021-02-04 18:24 ` Quentin Perret
2021-02-04 18:19 ` Quentin Perret
2021-02-04 18:24 ` Will Deacon
2021-02-04 18:32 ` Quentin Perret
2021-01-08 12:15 ` [RFC PATCH v2 13/26] KVM: arm64: Enable access to sanitized CPU features at EL2 Quentin Perret
2021-01-13 11:33 ` Marc Zyngier
2021-01-13 14:23 ` Quentin Perret
2021-01-13 14:35 ` Quentin Perret
2021-01-13 17:27 ` Marc Zyngier
2021-01-13 18:28 ` Quentin Perret
2021-01-08 12:15 ` [RFC PATCH v2 14/26] KVM: arm64: Factor out vector address calculation Quentin Perret
2021-02-02 18:24 ` Will Deacon
2021-01-08 12:15 ` [RFC PATCH v2 15/26] of/fdt: Introduce early_init_dt_add_memory_hyp() Quentin Perret
2021-01-11 14:45 ` Rob Herring
2021-01-12 9:51 ` Quentin Perret
2021-01-12 14:10 ` Rob Herring
2021-01-12 14:26 ` Quentin Perret
2021-01-12 15:53 ` Rob Herring
2021-01-12 16:15 ` Quentin Perret
2021-01-12 16:45 ` Rob Herring
2021-01-12 16:50 ` Quentin Perret
2021-01-15 11:49 ` Quentin Perret
2021-01-08 12:15 ` [RFC PATCH v2 16/26] KVM: arm64: Prepare Hyp memory protection Quentin Perret
2021-02-03 14:37 ` Will Deacon
2021-02-04 10:47 ` Quentin Perret
2021-02-05 17:56 ` Will Deacon [this message]
2021-02-09 10:00 ` Quentin Perret
2021-02-09 12:23 ` Will Deacon
2021-02-19 18:32 ` Sean Christopherson
2021-02-22 11:04 ` Quentin Perret
2021-01-08 12:15 ` [RFC PATCH v2 17/26] KVM: arm64: Elevate Hyp mappings creation at EL2 Quentin Perret
2021-02-03 15:31 ` Will Deacon
2021-02-04 11:08 ` Quentin Perret
2021-02-05 18:01 ` Will Deacon
2021-01-08 12:15 ` [RFC PATCH v2 18/26] KVM: arm64: Use kvm_arch for stage 2 pgtable Quentin Perret
2021-02-03 15:34 ` Will Deacon
2021-01-08 12:15 ` [RFC PATCH v2 19/26] KVM: arm64: Use kvm_arch in kvm_s2_mmu Quentin Perret
2021-02-03 15:38 ` Will Deacon
2021-01-08 12:15 ` [RFC PATCH v2 20/26] KVM: arm64: Set host stage 2 using kvm_nvhe_init_params Quentin Perret
2021-02-03 16:05 ` Will Deacon
2021-01-08 12:15 ` [RFC PATCH v2 21/26] KVM: arm64: Refactor kvm_arm_setup_stage2() Quentin Perret
2021-02-03 15:53 ` Will Deacon
2021-02-04 14:07 ` Quentin Perret
2021-01-08 12:15 ` [RFC PATCH v2 22/26] KVM: arm64: Refactor __load_guest_stage2() Quentin Perret
2021-02-03 15:54 ` Will Deacon
2021-01-08 12:15 ` [RFC PATCH v2 23/26] KVM: arm64: Refactor __populate_fault_info() Quentin Perret
2021-02-03 15:58 ` Will Deacon
2021-02-04 14:18 ` Quentin Perret
2021-01-08 12:15 ` [RFC PATCH v2 24/26] KVM: arm64: Make memcache anonymous in pgtable allocator Quentin Perret
2021-02-03 15:59 ` Will Deacon
2021-02-04 14:24 ` Quentin Perret
2021-02-04 14:36 ` Will Deacon
2021-01-08 12:15 ` [RFC PATCH v2 25/26] KVM: arm64: Reserve memory for host stage 2 Quentin Perret
2021-01-08 12:15 ` [RFC PATCH v2 26/26] KVM: arm64: Wrap the host with a " Quentin Perret
2021-02-03 16:11 ` Will Deacon
2021-02-04 14:26 ` Quentin Perret
2021-02-04 14:37 ` Will Deacon
2021-02-17 16:27 ` [RFC PATCH v2 00/26] KVM/arm64: A stage 2 for the host Mate Toth-Pal
2021-02-17 17:24 ` Quentin Perret
2021-02-19 17:54 ` Sean Christopherson
2021-02-19 17:57 ` Quentin Perret
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