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From: Quentin Perret <qperret@google.com>
To: Marc Zyngier <maz@kernel.org>
Cc: catalin.marinas@arm.com, will@kernel.org, james.morse@arm.com,
	julien.thierry.kdev@gmail.com, suzuki.poulose@arm.com,
	android-kvm@google.com, seanjc@google.com,
	linux-kernel@vger.kernel.org, robh+dt@kernel.org,
	linux-arm-kernel@lists.infradead.org, kernel-team@android.com,
	kvmarm@lists.cs.columbia.edu, tabba@google.com, ardb@kernel.org,
	mark.rutland@arm.com, dbrazdil@google.com, mate.toth-pal@arm.com
Subject: Re: [PATCH 1/2] KVM: arm64: Introduce KVM_PGTABLE_S2_NOFWB Stage-2 flag
Date: Wed, 17 Mar 2021 14:47:25 +0000	[thread overview]
Message-ID: <YFIWff9f+fESjIM2@google.com> (raw)
In-Reply-To: <87a6r1j10k.wl-maz@kernel.org>

On Wednesday 17 Mar 2021 at 14:41:31 (+0000), Marc Zyngier wrote:
> Hi Quentin,
> 
> On Wed, 17 Mar 2021 14:17:13 +0000,
> Quentin Perret <qperret@google.com> wrote:
> > 
> > In order to further configure stage-2 page-tables, pass flags to the
> > init function using a new enum.
> > 
> > The first of these flags allows to disable FWB even if the hardware
> > supports it as we will need to do so for the host stage-2.
> > 
> > Signed-off-by: Quentin Perret <qperret@google.com>
> > 
> > ---
> > 
> > One question is, do we want to use stage2_has_fwb() everywhere, including
> > guest-specific paths (e.g. kvm_arch_prepare_memory_region(), ...) ?
> > 
> > That'd make this patch more intrusive, but would make the whole codebase
> > work with FWB enabled on a guest by guest basis. I don't see us use that
> > anytime soon (other than maybe debug of some sort?) but it'd be good to
> > have an agreement.
> 
> I'm not sure how useful that would be. We fought long and hard to get
> FWB, and I can't see a good reason to disable it for guests unless the
> HW was buggy (but in which case that'd be for everyone). I'd rather
> keep the changes small for now (this whole series is invasive
> enough!).

OK, that works for me.

> As for this patch, I only have a few cosmetic comments:

Happy with the suggestions, I'll fold that in v6.

Cheers,
Quentin

  reply	other threads:[~2021-03-17 14:48 UTC|newest]

Thread overview: 60+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-15 14:35 [PATCH v5 00/36] KVM: arm64: A stage 2 for the host Quentin Perret
2021-03-15 14:35 ` [PATCH v5 01/36] arm64: lib: Annotate {clear,copy}_page() as position-independent Quentin Perret
2021-03-15 14:35 ` [PATCH v5 02/36] KVM: arm64: Link position-independent string routines into .hyp.text Quentin Perret
2021-03-15 14:35 ` [PATCH v5 03/36] arm64: kvm: Add standalone ticket spinlock implementation for use at hyp Quentin Perret
2021-03-15 14:35 ` [PATCH v5 04/36] KVM: arm64: Initialize kvm_nvhe_init_params early Quentin Perret
2021-03-15 14:35 ` [PATCH v5 05/36] KVM: arm64: Avoid free_page() in page-table allocator Quentin Perret
2021-03-15 14:35 ` [PATCH v5 06/36] KVM: arm64: Factor memory allocation out of pgtable.c Quentin Perret
2021-03-15 14:35 ` [PATCH v5 07/36] KVM: arm64: Introduce a BSS section for use at Hyp Quentin Perret
2021-03-15 14:35 ` [PATCH v5 08/36] KVM: arm64: Make kvm_call_hyp() a function call " Quentin Perret
2021-03-15 14:35 ` [PATCH v5 09/36] KVM: arm64: Allow using kvm_nvhe_sym() in hyp code Quentin Perret
2021-03-15 14:35 ` [PATCH v5 10/36] KVM: arm64: Introduce an early Hyp page allocator Quentin Perret
2021-03-15 14:35 ` [PATCH v5 11/36] KVM: arm64: Stub CONFIG_DEBUG_LIST at Hyp Quentin Perret
2021-03-15 14:35 ` [PATCH v5 12/36] KVM: arm64: Introduce a Hyp buddy page allocator Quentin Perret
2021-03-15 14:35 ` [PATCH v5 13/36] KVM: arm64: Enable access to sanitized CPU features at EL2 Quentin Perret
2021-03-15 14:35 ` [PATCH v5 14/36] KVM: arm64: Provide __flush_dcache_area " Quentin Perret
2021-03-15 16:33   ` Will Deacon
2021-03-15 16:56     ` Quentin Perret
2021-03-15 17:03       ` Will Deacon
2021-03-15 14:35 ` [PATCH v5 15/36] KVM: arm64: Factor out vector address calculation Quentin Perret
2021-03-15 14:35 ` [PATCH v5 16/36] arm64: asm: Provide set_sctlr_el2 macro Quentin Perret
2021-03-15 14:35 ` [PATCH v5 17/36] KVM: arm64: Prepare the creation of s1 mappings at EL2 Quentin Perret
2021-03-15 14:35 ` [PATCH v5 18/36] KVM: arm64: Elevate hypervisor mappings creation " Quentin Perret
2021-03-15 14:35 ` [PATCH v5 19/36] KVM: arm64: Use kvm_arch for stage 2 pgtable Quentin Perret
2021-03-15 14:35 ` [PATCH v5 20/36] KVM: arm64: Use kvm_arch in kvm_s2_mmu Quentin Perret
2021-03-15 14:35 ` [PATCH v5 21/36] KVM: arm64: Set host stage 2 using kvm_nvhe_init_params Quentin Perret
2021-03-15 14:35 ` [PATCH v5 22/36] KVM: arm64: Refactor kvm_arm_setup_stage2() Quentin Perret
2021-03-15 14:35 ` [PATCH v5 23/36] KVM: arm64: Refactor __load_guest_stage2() Quentin Perret
2021-03-15 14:35 ` [PATCH v5 24/36] KVM: arm64: Refactor __populate_fault_info() Quentin Perret
2021-03-15 14:35 ` [PATCH v5 25/36] KVM: arm64: Make memcache anonymous in pgtable allocator Quentin Perret
2021-03-15 14:35 ` [PATCH v5 26/36] KVM: arm64: Reserve memory for host stage 2 Quentin Perret
2021-03-15 14:35 ` [PATCH v5 27/36] KVM: arm64: Sort the hypervisor memblocks Quentin Perret
2021-03-15 14:35 ` [PATCH v5 28/36] KVM: arm64: Always zero invalid PTEs Quentin Perret
2021-03-15 14:35 ` [PATCH v5 29/36] KVM: arm64: Use page-table to track page ownership Quentin Perret
2021-03-15 16:36   ` Will Deacon
2021-03-15 16:53     ` Quentin Perret
2021-03-15 17:01       ` Will Deacon
2021-03-15 14:35 ` [PATCH v5 30/36] KVM: arm64: Refactor the *_map_set_prot_attr() helpers Quentin Perret
2021-03-15 14:35 ` [PATCH v5 31/36] KVM: arm64: Add kvm_pgtable_stage2_find_range() Quentin Perret
2021-03-15 16:31   ` Will Deacon
2021-03-15 14:35 ` [PATCH v5 32/36] KVM: arm64: Provide sanitized mmfr* registers at EL2 Quentin Perret
2021-03-15 16:31   ` Will Deacon
2021-03-15 14:35 ` [PATCH v5 33/36] KVM: arm64: Wrap the host with a stage 2 Quentin Perret
2021-03-16 12:28   ` Mate Toth-Pal
2021-03-16 12:53     ` Quentin Perret
2021-03-16 14:29       ` Quentin Perret
2021-03-16 15:16         ` Mate Toth-Pal
2021-03-16 17:46           ` Quentin Perret
2021-03-17  8:41             ` Mate Toth-Pal
2021-03-17  9:02               ` Quentin Perret
2021-03-17 14:57                 ` Mate Toth-Pal
2021-03-17 14:17   ` [PATCH 0/2] Fixes for FWB Quentin Perret
2021-03-17 14:17     ` [PATCH 1/2] KVM: arm64: Introduce KVM_PGTABLE_S2_NOFWB Stage-2 flag Quentin Perret
2021-03-17 14:41       ` Marc Zyngier
2021-03-17 14:47         ` Quentin Perret [this message]
2021-03-17 14:42       ` Will Deacon
2021-03-17 14:51         ` Quentin Perret
2021-03-17 14:17     ` [PATCH 2/2] KVM: arm64: Disable FWB in host stage-2 Quentin Perret
2021-03-15 14:35 ` [PATCH v5 34/36] KVM: arm64: Page-align the .hyp sections Quentin Perret
2021-03-15 14:35 ` [PATCH v5 35/36] KVM: arm64: Disable PMU support in protected mode Quentin Perret
2021-03-15 14:35 ` [PATCH v5 36/36] KVM: arm64: Protect the .hyp sections from the host Quentin Perret

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