From: Mark Rutland <mark.rutland@arm.com>
To: Sven Schnelle <svens@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>,
Paolo Bonzini <pbonzini@redhat.com>,
linux-kernel@vger.kernel.org, aleksandar.qemu.devel@gmail.com,
alexandru.elisei@arm.com, anup.patel@wdc.com,
aou@eecs.berkeley.edu, atish.patra@wdc.com,
benh@kernel.crashing.org, bp@alien8.de, catalin.marinas@arm.com,
chenhuacai@kernel.org, dave.hansen@linux.intel.com,
david@redhat.com, frankja@linux.ibm.com, frederic@kernel.org,
gor@linux.ibm.com, hca@linux.ibm.com, imbrenda@linux.ibm.com,
james.morse@arm.com, jmattson@google.com, joro@8bytes.org,
kvm@vger.kernel.org, maz@kernel.org, mingo@redhat.com,
mpe@ellerman.id.au, nsaenzju@redhat.com, palmer@dabbelt.com,
paulmck@kernel.org, paulus@samba.org, paul.walmsley@sifive.com,
seanjc@google.com, suzuki.poulose@arm.com, tglx@linutronix.de,
tsbogend@alpha.franken.de, vkuznets@redhat.com,
wanpengli@tencent.com, will@kernel.org
Subject: Re: [PATCH 0/5] kvm: fix latent guest entry/exit bugs
Date: Tue, 18 Jan 2022 18:12:40 +0000 [thread overview]
Message-ID: <20220118181240.GF17938@C02TD0UTHF1T.local> (raw)
In-Reply-To: <20220118175051.GE17938@C02TD0UTHF1T.local>
On Tue, Jan 18, 2022 at 05:50:51PM +0000, Mark Rutland wrote:
> On Tue, Jan 18, 2022 at 05:09:25PM +0100, Sven Schnelle wrote:
> > I wonder whether the code in irqentry_enter() should call a function
> > is_eqs() instead of is_idle_task(). The default implementation would
> > be just a
> >
> > #ifndef is_eqs
> > #define is_eqs is_idle_task
> > #endif
> >
> > and if an architecture has special requirements, it could just define
> > is_eqs() and do the required checks there. This way the architecture
> > could define whether it's a percpu bit, a cpu flag or something else.
>
> I had come to almost the same approach: I've added an arch_in_rcu_eqs()
> which is checked in addition to the existing is_idle_thread() check.
>
> In the case of checking is_idle_thread() and checking for PF_VCPU, I'm
> assuming the compiler can merge the loads of current->flags, and there's
> little gain by making this entirely architecture specific, but we can
> always check that and/or reconsider in future.
FWIW, I've pushed out my WIP to:
https://git.kernel.org/pub/scm/linux/kernel/git/mark/linux.git/log/?h=kvm/entry-rework
... and I intend to clean that up and get it out on the list tomorrow.
The new entry/exit helpers are:
https://git.kernel.org/pub/scm/linux/kernel/git/mark/linux.git/commit/?h=kvm/entry-rework&id=df292ecabba50145849d8c8888cec9153267b31d
The arch_in_rcu_eqs() bit is:
https://git.kernel.org/pub/scm/linux/kernel/git/mark/linux.git/commit/?h=kvm/entry-rework&id=6e24c5ed7558ee7a4c95dfe62891dfdc51e6c6c4
The s390 changes are:
https://git.kernel.org/pub/scm/linux/kernel/git/mark/linux.git/commit/?h=kvm/entry-rework&id=ca8daba1809b6e4f1be425ca93f6373a2ea0af6b
I need to clean up the commit messages (including typos, TODOs, and
deleting some stale gunk), and there are some comments to write, but by
and large I think the structure is about right.
Thanks,
Mark.
next prev parent reply other threads:[~2022-01-18 18:12 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-11 15:35 [PATCH 0/5] kvm: fix latent guest entry/exit bugs Mark Rutland
2022-01-11 15:35 ` [PATCH 1/5] kvm: add exit_to_guest_mode() and enter_from_guest_mode() Mark Rutland
2022-01-11 17:54 ` Marc Zyngier
2022-01-13 11:01 ` Mark Rutland
2022-01-13 11:55 ` Marc Zyngier
2022-01-13 13:01 ` Mark Rutland
2022-01-13 20:32 ` Sean Christopherson
2022-01-14 11:48 ` Mark Rutland
2022-01-14 16:11 ` Sean Christopherson
2022-01-18 13:01 ` Mark Rutland
2022-01-11 15:35 ` [PATCH 2/5] kvm/arm64: rework guest entry logic Mark Rutland
2022-01-11 17:55 ` Marc Zyngier
2022-01-13 11:17 ` Mark Rutland
2022-01-13 11:43 ` Marc Zyngier
2022-01-13 12:58 ` Mark Rutland
2022-01-11 15:35 ` [PATCH 3/5] kvm/mips: " Mark Rutland
2022-01-11 15:35 ` [PATCH 4/5] kvm/riscv: " Mark Rutland
2022-01-11 15:35 ` [PATCH 5/5] kvm/x86: " Mark Rutland
2022-01-13 20:50 ` Sean Christopherson
2022-01-14 12:05 ` Mark Rutland
2022-01-14 16:49 ` Sean Christopherson
2022-01-11 18:47 ` [PATCH 0/5] kvm: fix latent guest entry/exit bugs Palmer Dabbelt
2022-01-13 15:20 ` Christian Borntraeger
2022-01-14 12:19 ` Mark Rutland
2022-01-14 12:29 ` Christian Borntraeger
2022-01-14 13:32 ` Mark Rutland
2022-01-14 13:51 ` Christian Borntraeger
2022-01-14 15:19 ` Mark Rutland
2022-01-17 17:45 ` Paolo Bonzini
2022-01-18 12:02 ` Mark Rutland
2022-01-18 12:08 ` Christian Borntraeger
2022-01-18 12:42 ` Christian Borntraeger
2022-01-18 13:12 ` Mark Rutland
2022-01-18 14:15 ` Christian Borntraeger
2022-01-18 15:43 ` Mark Rutland
2022-01-18 16:09 ` Sven Schnelle
2022-01-18 17:50 ` Mark Rutland
2022-01-18 18:12 ` Mark Rutland [this message]
2022-01-19 6:41 ` Sven Schnelle
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