RE: [PATCH 34/39] arm64: psci: Ignore DENIED CPUs

Jianyong Wu
2023-11-21T01:44:30Z

> -----Original Message-----
> From: Russell King <linux@armlinux.org.uk>
> Sent: 2023年11月20日 17:58
> To: Jianyong Wu <Jianyong.Wu@arm.com>
> Cc: linux-pm@vger.kernel.org; loongarch@lists.linux.dev;
> linux-acpi@vger.kernel.org; linux-arch@vger.kernel.org;
> linux-kernel@vger.kernel.org; linux-arm-kernel@lists.infradead.org;
> linux-riscv@lists.infradead.org; kvmarm@lists.linux.dev; x86@kernel.org;
> linux-csky@vger.kernel.org; linux-doc@vger.kernel.org;
> linux-ia64@vger.kernel.org; linux-parisc@vger.kernel.org; Salil Mehta
> <salil.mehta@huawei.com>; Jean-Philippe Brucker <jean-philippe@linaro.org>;
> Justin He <Justin.He@arm.com>; James Morse <James.Morse@arm.com>;
> Catalin Marinas <Catalin.Marinas@arm.com>; Will Deacon <will@kernel.org>;
> Mark Rutland <Mark.Rutland@arm.com>; Lorenzo Pieralisi
> <lpieralisi@kernel.org>
> Subject: Re: [PATCH 34/39] arm64: psci: Ignore DENIED CPUs
>
> On Mon, Nov 20, 2023 at 09:36:05AM +0000, Jianyong Wu wrote:
> >
> >
> > > -----Original Message-----
> > > From: Russell King <linux@armlinux.org.uk>
> > > Sent: 2023年11月20日 17:25
> > > To: Jianyong Wu <Jianyong.Wu@arm.com>
> > > Cc: linux-pm@vger.kernel.org; loongarch@lists.linux.dev;
> > > linux-acpi@vger.kernel.org; linux-arch@vger.kernel.org;
> > > linux-kernel@vger.kernel.org; linux-arm-kernel@lists.infradead.org;
> > > linux-riscv@lists.infradead.org; kvmarm@lists.linux.dev;
> > > x86@kernel.org; linux-csky@vger.kernel.org;
> > > linux-doc@vger.kernel.org; linux-ia64@vger.kernel.org;
> > > linux-parisc@vger.kernel.org; Salil Mehta <salil.mehta@huawei.com>;
> > > Jean-Philippe Brucker <jean-philippe@linaro.org>; Justin He
> > > <Justin.He@arm.com>; James Morse <James.Morse@arm.com>; Catalin
> > > Marinas <Catalin.Marinas@arm.com>; Will Deacon <will@kernel.org>;
> > > Mark Rutland <Mark.Rutland@arm.com>; Lorenzo Pieralisi
> > > <lpieralisi@kernel.org>
> > > Subject: Re: [PATCH 34/39] arm64: psci: Ignore DENIED CPUs
> > >
> > > On Thu, Nov 16, 2023 at 07:45:51AM +0000, Jianyong Wu wrote:
> > > > Hi Russell,
> > > >
> > > > One inline comment.
> > > ...
> > > > > Changes since RFC v2
> > > > > * Add specification reference
> > > > > * Use EPERM rather than EPROBE_DEFER
> > > ...
> > > > > @@ -40,7 +40,7 @@ static int cpu_psci_cpu_boot(unsigned int cpu) {
> > > > > phys_addr_t pa_secondary_entry = __pa_symbol(secondary_entry);
> > > > > int err = psci_ops.cpu_on(cpu_logical_map(cpu),
> pa_secondary_entry);
> > > > > - if (err)
> > > > > + if (err && err != -EPROBE_DEFER)
> > > >
> > > > Should this be EPERM? As the following psci cpu_on op will return it.
> > > > I think you miss to change this when apply Jean-Philippe's patch.
> > >
> > > It looks like James didn't properly update all places. Also,
> > >
> > > > > diff --git a/drivers/firmware/psci/psci.c
> > > > > b/drivers/firmware/psci/psci.c index d9629ff87861..ee82e7880d8c
> > > > > 100644
> > > > > --- a/drivers/firmware/psci/psci.c
> > > > > +++ b/drivers/firmware/psci/psci.c
> > > > > @@ -218,6 +218,8 @@ static int __psci_cpu_on(u32 fn, unsigned
> > > > > long cpuid, unsigned long entry_point)
> > > > > int err;
> > > > >
> > > > > err = invoke_psci_fn(fn, cpuid, entry_point, 0);
> > > > > + if (err == PSCI_RET_DENIED)
> > > > > + return -EPERM;
> > > > > return psci_to_linux_errno(err);
> > >
> > > This change is unnecessary - probably comes from when -EPROBE_DEFER
> > > was being used. psci_to_linux_errno() already does:
> >
> > But may print lots of noise like:
> >
> > [ 0.008955] smp: Bringing up secondary CPUs ...
> > [ 0.009661] psci: failed to boot CPU1 (-1)
> > [ 0.010360] psci: failed to boot CPU2 (-1)
> > [ 0.011164] psci: failed to boot CPU3 (-1)
> > [ 0.011946] psci: failed to boot CPU4 (-1)
> > [ 0.012764] psci: failed to boot CPU5 (-1)
> > [ 0.013534] psci: failed to boot CPU6 (-1)
> > [ 0.014349] psci: failed to boot CPU7 (-1)
> > [ 0.014820] smp: Brought up 1 node, 1 CPU
> >
> > Is this expected?
>
> Please read my email again, and take note of the _context_ above the places
> that I've commented. Context matters.
>
> What I'm saying is that this change:
>
> err = invoke_psci_fn(fn, cpuid, entry_point, 0);
> + if (err == PSCI_RET_DENIED)
> + return -EPERM;
> return psci_to_linux_errno(err);
>
> Is unnecessary when psci_to_linux_errno() already does:
>
> static __always_inline int psci_to_linux_errno(int errno) {
> switch (errno) {
> ...
> case PSCI_RET_DENIED:
> return -EPERM;
>
> So, a return of PSCI_RET_DENIED from invoke_psci_fn() above will _already_ be
> translated to -EPERM (which is -1) by psci_to_linux_errno(). There is no need to
> add that extra if() statement in __psci_cpu_on().
>
> I was _not_ saying that the entire patch was unnecessary.
>
> Context matters. That's why we include context in replies.
>
> Standard email etiquette (before Microsoft messed it up) is to quote the email
> that is being replied to, trimming hard irrelevant content, and to place the reply
> comments immediately below the original content to which the comments
> relate, to give the reply comments the context necessary for correct
> interpretation.
>

Oh, sorry, my mistake. Ignore my last comment.

Thanks
Jianyong

> Thanks.
>
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