From: Catalin Marinas <catalin.marinas@arm.com>
To: Steven Price <steven.price@arm.com>
Cc: Marc Zyngier <maz@kernel.org>, Will Deacon <will@kernel.org>,
James Morse <james.morse@arm.com>,
Julien Thierry <julien.thierry.kdev@gmail.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
kvmarm@lists.cs.columbia.edu,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, Dave Martin <Dave.Martin@arm.com>,
Mark Rutland <mark.rutland@arm.com>,
Thomas Gleixner <tglx@linutronix.de>,
qemu-devel@nongnu.org, Juan Quintela <quintela@redhat.com>,
"Dr. David Alan Gilbert" <dgilbert@redhat.com>,
Richard Henderson <richard.henderson@linaro.org>,
Peter Maydell <peter.maydell@linaro.org>,
Haibo Xu <Haibo.Xu@arm.com>, Andrew Jones <drjones@redhat.com>
Subject: Re: [PATCH v12 3/8] arm64: mte: Sync tags for pages where PTE is untagged
Date: Thu, 20 May 2021 14:02:25 +0100 [thread overview]
Message-ID: <20210520130224.GE12251@arm.com> (raw)
In-Reply-To: <20210520122550.GD12251@arm.com>
On Thu, May 20, 2021 at 01:25:50PM +0100, Catalin Marinas wrote:
> On Thu, May 20, 2021 at 12:55:21PM +0100, Steven Price wrote:
> > The problem I hit is one of include dependencies:
> >
> > is_swap_pte() is defined (as a static inline) in
> > include/linux/swapops.h. However the definition depends on
> > pte_none()/pte_present() which are defined in pgtable.h - so there's a
> > circular dependency.
> >
> > Open coding is_swap_pte() in set_pte_at() works, but it's a bit ugly.
> > Any ideas on how to improve on the below?
> >
> > if (system_supports_mte() && pte_present(pte) &&
> > pte_access_permitted(pte, false) && !pte_special(pte)) {
> > pte_t old_pte = READ_ONCE(*ptep);
> > /*
> > * We only need to synchronise if the new PTE has tags enabled
> > * or if swapping in (in which case another mapping may have
> > * set tags in the past even if this PTE isn't tagged).
> > * (!pte_none() && !pte_present()) is an open coded version of
> > * is_swap_pte()
> > */
> > if (pte_tagged(pte) || (!pte_none(pte) && !pte_present(pte)))
> > mte_sync_tags(old_pte, pte);
> > }
>
> That's why I avoided testing my suggestion ;). I think we should just
> add !pte_none() in there with a comment that it may be a swap pte and
> use the is_swap_pte() again on the mte_sync_tags() path. We already have
> the pte_present() check.
Correction - pte_present() checks the new pte only, we need another for
the old pte. So it looks like we'll open-code is_swap_pte().
--
Catalin
next prev parent reply other threads:[~2021-05-20 13:03 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-17 12:32 [PATCH v12 0/8] MTE support for KVM guest Steven Price
2021-05-17 12:32 ` [PATCH v12 1/8] arm64: mte: Handle race when synchronising tags Steven Price
2021-05-17 14:03 ` Marc Zyngier
2021-05-17 14:56 ` Steven Price
2021-05-19 17:32 ` Catalin Marinas
2021-05-17 12:32 ` [PATCH v12 2/8] arm64: Handle MTE tags zeroing in __alloc_zeroed_user_highpage() Steven Price
2021-05-17 12:32 ` [PATCH v12 3/8] arm64: mte: Sync tags for pages where PTE is untagged Steven Price
2021-05-17 16:14 ` Marc Zyngier
2021-05-19 9:32 ` Steven Price
2021-05-19 17:48 ` Catalin Marinas
2021-05-19 18:06 ` Catalin Marinas
2021-05-20 11:55 ` Steven Price
2021-05-20 12:25 ` Catalin Marinas
2021-05-20 13:02 ` Catalin Marinas [this message]
2021-05-20 13:03 ` Steven Price
2021-05-17 12:32 ` [PATCH v12 4/8] arm64: kvm: Introduce MTE VM feature Steven Price
2021-05-17 16:45 ` Marc Zyngier
2021-05-19 10:48 ` Steven Price
2021-05-20 8:51 ` Marc Zyngier
2021-05-20 14:46 ` Steven Price
2021-05-20 11:54 ` Catalin Marinas
2021-05-20 15:05 ` Steven Price
2021-05-20 17:50 ` Catalin Marinas
2021-05-21 9:28 ` Steven Price
2021-05-17 12:32 ` [PATCH v12 5/8] arm64: kvm: Save/restore MTE registers Steven Price
2021-05-17 17:17 ` Marc Zyngier
2021-05-19 13:04 ` Steven Price
2021-05-20 9:46 ` Marc Zyngier
2021-05-20 15:21 ` Steven Price
2021-05-17 12:32 ` [PATCH v12 6/8] arm64: kvm: Expose KVM_ARM_CAP_MTE Steven Price
2021-05-17 17:40 ` Marc Zyngier
2021-05-19 13:26 ` Steven Price
2021-05-20 10:09 ` Marc Zyngier
2021-05-20 10:51 ` Steven Price
2021-05-17 12:32 ` [PATCH v12 7/8] KVM: arm64: ioctl to fetch/store tags in a guest Steven Price
2021-05-17 18:04 ` Marc Zyngier
2021-05-19 13:51 ` Steven Price
2021-05-20 12:05 ` Catalin Marinas
2021-05-20 15:58 ` Steven Price
2021-05-20 17:27 ` Catalin Marinas
2021-05-21 9:42 ` Steven Price
2021-05-24 18:11 ` Catalin Marinas
2021-05-27 7:50 ` Steven Price
2021-05-27 13:08 ` Catalin Marinas
2021-05-17 12:32 ` [PATCH v12 8/8] KVM: arm64: Document MTE capability and ioctl Steven Price
2021-05-17 18:09 ` Marc Zyngier
2021-05-19 14:09 ` Steven Price
2021-05-20 10:24 ` Marc Zyngier
2021-05-20 10:52 ` Steven Price
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