From: Quentin Perret <qperret@google.com>
To: Marc Zyngier <maz@kernel.org>
Cc: kernel-team@android.com, qwandor@google.com, will@kernel.org,
catalin.marinas@arm.com, linux-kernel@vger.kernel.org,
kvmarm@lists.cs.columbia.edu,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 03/14] KVM: arm64: Continue stage-2 map when re-creating mappings
Date: Tue, 20 Jul 2021 12:56:52 +0100 [thread overview]
Message-ID: <YPa6BGuUFjw8do+o@google.com> (raw)
In-Reply-To: <875yx59ysd.wl-maz@kernel.org>
On Tuesday 20 Jul 2021 at 09:26:10 (+0100), Marc Zyngier wrote:
> Right, but this is on a different path, right? Guests can never fault
> multiple mappings at once, and it takes you a host hypercall to
> perform this "multiple leaves at once".
Right.
> Is there any way we can restrict this to the hypercall? Or even
> better, keep the hypercall as a "one page at a time" thing? I can't
> imagine it being performance critical (it is a once-off, and only used
> over a rather small region of memory). Then, the called doesn't have
> to worry about the page already being mapped or not. This would also
> match the behaviour of what I do on the MMIO side.
>
> Or do you anticipate much gain from this being able to use block
> mappings?
Not really no, especially given that mappings of shared pages will be
forced to page granularity thanks to the other patch we discussed in
this series. I was just hoping to reduce the overhead a bit by reducing
the number of hypercalls. But as you said, this probably doesn't matter
all that much, so happy to rework that. I'll look into making the hcall
use one page at a time, and hopefully that'll simplify a few other
things in the check_host_share_hyp() path near the end of this series.
Thanks,
Quentin
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next prev parent reply other threads:[~2021-07-20 11:57 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-19 10:47 [PATCH 00/14] Track shared pages at EL2 in protected mode Quentin Perret
2021-07-19 10:47 ` [PATCH 01/14] KVM: arm64: Provide the host_stage2_try() helper macro Quentin Perret
2021-07-20 13:57 ` Fuad Tabba
2021-07-19 10:47 ` [PATCH 02/14] KVM: arm64: Optimize kvm_pgtable_stage2_find_range() Quentin Perret
2021-07-19 10:47 ` [PATCH 03/14] KVM: arm64: Continue stage-2 map when re-creating mappings Quentin Perret
2021-07-19 12:14 ` Marc Zyngier
2021-07-19 13:32 ` Quentin Perret
2021-07-20 8:26 ` Marc Zyngier
2021-07-20 11:56 ` Quentin Perret [this message]
2021-07-19 10:47 ` [PATCH 04/14] KVM: arm64: Rename KVM_PTE_LEAF_ATTR_S2_IGNORED Quentin Perret
2021-07-19 10:47 ` [PATCH 05/14] KVM: arm64: Don't overwrite ignored bits with owner id Quentin Perret
2021-07-19 12:55 ` Marc Zyngier
2021-07-19 13:39 ` Quentin Perret
2021-07-20 8:46 ` Marc Zyngier
2021-07-19 10:47 ` [PATCH 06/14] KVM: arm64: Tolerate re-creating hyp mappings to set ignored bits Quentin Perret
2021-07-20 10:17 ` Fuad Tabba
2021-07-20 10:30 ` Quentin Perret
2021-07-20 10:59 ` Fuad Tabba
2021-07-20 11:14 ` Quentin Perret
2021-07-19 10:47 ` [PATCH 07/14] KVM: arm64: Enable forcing page-level stage-2 mappings Quentin Perret
2021-07-19 14:24 ` Marc Zyngier
2021-07-19 15:36 ` Quentin Perret
2021-07-19 10:47 ` [PATCH 08/14] KVM: arm64: Add support for tagging shared pages in page-table Quentin Perret
2021-07-19 14:43 ` Marc Zyngier
2021-07-19 15:49 ` Quentin Perret
2021-07-20 10:13 ` Marc Zyngier
2021-07-20 11:48 ` Quentin Perret
2021-07-20 13:48 ` Fuad Tabba
2021-07-20 14:06 ` Quentin Perret
2021-07-21 7:34 ` Fuad Tabba
2021-07-19 10:47 ` [PATCH 09/14] KVM: arm64: Mark host bss and rodata section as shared Quentin Perret
2021-07-19 15:01 ` Marc Zyngier
2021-07-19 15:56 ` Quentin Perret
2021-07-19 10:47 ` [PATCH 10/14] KVM: arm64: Enable retrieving protections attributes of PTEs Quentin Perret
2021-07-19 10:47 ` [PATCH 11/14] KVM: arm64: Expose kvm_pte_valid() helper Quentin Perret
2021-07-21 8:20 ` Fuad Tabba
2021-07-19 10:47 ` [PATCH 12/14] KVM: arm64: Refactor pkvm_pgtable locking Quentin Perret
2021-07-21 8:37 ` Fuad Tabba
2021-07-19 10:47 ` [PATCH 13/14] KVM: arm64: Restrict hyp stage-1 manipulation in protected mode Quentin Perret
2021-07-21 10:45 ` Fuad Tabba
2021-07-21 13:35 ` Quentin Perret
2021-07-19 10:47 ` [PATCH 14/14] KVM: arm64: Prevent late calls to __pkvm_create_private_mapping() Quentin Perret
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