From: Mark Rutland <mark.rutland@arm.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>,
linux-kernel@vger.kernel.org,
Michael Ellerman <mpe@ellerman.id.au>,
aleksandar.qemu.devel@gmail.com, alexandru.elisei@arm.com,
anup.patel@wdc.com, aou@eecs.berkeley.edu, atish.patra@wdc.com,
bp@alien8.de, catalin.marinas@arm.com, chenhuacai@kernel.org,
dave.hansen@linux.intel.com, frankja@linux.ibm.com,
frederic@kernel.org, gor@linux.ibm.com, hca@linux.ibm.com,
james.morse@arm.com, jmattson@google.com, joro@8bytes.org,
luto@kernel.org, maz@kernel.org, mingo@redhat.com,
nsaenzju@redhat.com, palmer@dabbelt.com, paulmck@kernel.org,
paul.walmsley@sifive.com, peterz@infradead.org,
seanjc@google.com, suzuki.poulose@arm.com, svens@linux.ibm.com,
tglx@linutronix.de, tsbogend@alpha.franken.de,
vkuznets@redhat.com, wanpengli@tencent.com, will@kernel.org,
Anup Patel <anup@brainfault.org>,
Atish Patra <atishp@atishpatra.org>
Subject: Re: [PATCH v2 0/7] kvm: fix latent guest entry/exit bugs
Date: Thu, 20 Jan 2022 12:03:40 +0000 [thread overview]
Message-ID: <YelPnGM4kONm7ZQa@FVFF77S0Q05N> (raw)
In-Reply-To: <2688b779-9cb8-b6ea-f8cc-93bc8ddf72f3@redhat.com>
On Thu, Jan 20, 2022 at 12:28:09PM +0100, Paolo Bonzini wrote:
> On 1/19/22 20:22, Mark Rutland wrote:
> > I wonder, is the s390 guest entry/exit*preemptible* ?
> >
> > If a timer IRQ can preempt in the middle of the EQS, we wouldn't balance
> > things before a ctx-switch to the idle thread, which would then be able
> > to hit this.
> >
> > I'll need to go audit the other architectures for similar.
>
> They don't enable interrupts in the entry/exit path so they should be okay.
True.
So it sounds like for s390 adding an explicit preempt_{disable,enable}() is the
right thing to do. I'll add that and explanatory commentary.
> RISC-V and x86 have an explicit preempt_disable/enable, while MIPS only has
> local_irq_disable/enable.
>
> (MIPS is a mess of dead code, I have patches to clean it up).
Sure; I haven't wrapped my head around ppc yet, but I assume they keep
interrupts disabled as with the other simple cases.
Thanks,
Mark.
next prev parent reply other threads:[~2022-01-20 12:03 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-19 10:58 Mark Rutland
2022-01-19 10:58 ` [PATCH v2 1/7] entry: add arch_in_rcu_eqs() Mark Rutland
2022-01-19 17:35 ` Christian Borntraeger
2022-01-21 17:34 ` Nicolas Saenz Julienne
2022-01-19 10:58 ` [PATCH v2 2/7] kvm: add guest_state_{enter,exit}_irqoff() Mark Rutland
2022-01-20 11:00 ` Paolo Bonzini
2022-01-21 17:35 ` Nicolas Saenz Julienne
2022-01-19 10:58 ` [PATCH v2 3/7] kvm/arm64: rework guest entry logic Mark Rutland
2022-01-21 17:37 ` Nicolas Saenz Julienne
2022-01-19 10:58 ` [PATCH v2 4/7] kvm/mips: " Mark Rutland
2022-01-20 11:10 ` Paolo Bonzini
2022-01-20 13:33 ` Mark Rutland
2022-01-20 16:44 ` Mark Rutland
2022-01-20 16:57 ` Paolo Bonzini
2022-01-20 17:15 ` Mark Rutland
2022-01-20 17:17 ` Sean Christopherson
2022-01-20 17:29 ` Paolo Bonzini
2022-01-21 12:44 ` Mark Rutland
2022-01-19 10:58 ` [PATCH v2 5/7] kvm/riscv: " Mark Rutland
2022-01-20 11:18 ` Paolo Bonzini
2022-01-20 12:56 ` Mark Rutland
2022-01-20 13:13 ` Paolo Bonzini
2022-01-19 10:58 ` [PATCH v2 6/7] kvm/s390: " Mark Rutland
2022-01-19 10:58 ` [PATCH v2 7/7] kvm/x86: " Mark Rutland
2022-01-20 11:20 ` Paolo Bonzini
2022-01-21 17:40 ` Nicolas Saenz Julienne
2022-01-19 18:25 ` [PATCH v2 0/7] kvm: fix latent guest entry/exit bugs Christian Borntraeger
2022-01-19 18:28 ` Christian Borntraeger
2022-01-19 19:22 ` Mark Rutland
2022-01-19 19:30 ` Christian Borntraeger
2022-01-20 11:57 ` Mark Rutland
2022-01-20 12:02 ` Christian Borntraeger
2022-01-20 11:28 ` Paolo Bonzini
2022-01-20 12:03 ` Mark Rutland [this message]
2022-01-20 15:14 ` Christian Borntraeger
2022-01-21 9:53 ` Christian Borntraeger
2022-01-21 14:17 ` Christian Borntraeger
2022-01-21 14:30 ` Mark Rutland
2022-01-21 14:42 ` Christian Borntraeger
2022-01-21 15:29 ` Mark Rutland
2022-01-21 15:40 ` Christian Borntraeger
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