Re: [PATCH -next] irq-chip/gic-v3-its: Fixed an issue where the ITS executes the residual commands in the queue again when the ITS wakes up from sleep mode.

[xuqiang (M)]

在 2020/11/8 0:54, Marc Zyngier 写道:
> [dropping Jason, whose email address has been bouncing for weeks now]
>
> On 2020-11-07 10:42, Xu Qiang wrote:
> > On my platform, ITS_FLAGS_SAVE_SUSPEND_STATE is not set,thus do nothing
>
> Which platform?
Hisi Ascend platform
> > in its suspend and resuse function.On the other hand,firmware stores
> > GITS_CTRL,GITS_CBASER,GITS_CWRITER and GITS_BASER<n> in the suspend,
> > and restores these registers in the resume. As a result, the ITS 
> > executes
> > the residual commands in the queue.
>
> Which firmware are you using? I just had a look at the trusted 
> firmware source
> code, and while it definitely does something that *looks* like what 
> you are
> describing, it doesn't re-enable the ITS on resume.
>
> So what are you running?

I am using ATF. Since ITS_FLAGS_SAVE_SUSPEND_STATE is not set,ITS driver 
of OS will

not re-enable ITS in th resume. To make ITS work properly, we changed 
the ATF code

to re-enable ITS on resume.

> > Memory corruption may occur in the following scenarios:
> >
> > The kernel sends three commands in the following sequence:
> > 1.mapd(deviceA, ITT_addr1, valid:1)
> > 2.mapti(deviceA):ITS write ITT_addr1 memory;
> > 3.mapd(deviceA, ITT_addr1, valid:0) and kfree(ITT_addr1);
>
> The ITS doesn't 'kfree' stuff.
ITS driver kfree ITT_addr1.
> > 4.mapd(deviceA, ITT_addr2, valid:1);
> > 5.mapti(deviceA):ITS write ITT_addr2 memory;
>
> I don't think this example is relevant. The core of the problem is that
> the ITS gets re-enabled by your firmware. What are the affected systems?
>
> > To solve this problem,dropping the checks for 
> > ITS_FLAGS_SAVE_SUSPEND_STATE.
> >
> > Signed-off-by: Xu Qiang <xuqiang36@xxxxxxxxxx>
> > ---
> >  drivers/irqchip/irq-gic-v3-its.c | 13 -------------
> >  1 file changed, 13 deletions(-)
> >
> > diff --git a/drivers/irqchip/irq-gic-v3-its.c 
> > b/drivers/irqchip/irq-gic-v3-its.c
> > index 0fec31931e11..06f2c1c252b9 100644
> > --- a/drivers/irqchip/irq-gic-v3-its.c
> > +++ b/drivers/irqchip/irq-gic-v3-its.c
> > @@ -42,7 +42,6 @@
> >  #define ITS_FLAGS_CMDQ_NEEDS_FLUSHING        (1ULL << 0)
> >  #define ITS_FLAGS_WORKAROUND_CAVIUM_22375    (1ULL << 1)
> >  #define ITS_FLAGS_WORKAROUND_CAVIUM_23144    (1ULL << 2)
> > -#define ITS_FLAGS_SAVE_SUSPEND_STATE        (1ULL << 3)
> >
> >  #define RDIST_FLAGS_PROPBASE_NEEDS_FLUSHING    (1 << 0)
> >  #define RDIST_FLAGS_RD_TABLES_PREALLOCATED    (1 << 1)
> > @@ -4741,9 +4740,6 @@ static int its_save_disable(void)
> >      list_for_each_entry(its, &its_nodes, entry) {
> >          void __iomem *base;
> >
> > -        if (!(its->flags & ITS_FLAGS_SAVE_SUSPEND_STATE))
> > -            continue;
> > -
> >          base = its->base;
> >          its->ctlr_save = readl_relaxed(base + GITS_CTLR);
> >          err = its_force_quiescent(base);
> > @@ -4762,9 +4758,6 @@ static int its_save_disable(void)
> >          list_for_each_entry_continue_reverse(its, &its_nodes, entry) {
> >              void __iomem *base;
> >
> > -            if (!(its->flags & ITS_FLAGS_SAVE_SUSPEND_STATE))
> > -                continue;
> > -
> >              base = its->base;
> >              writel_relaxed(its->ctlr_save, base + GITS_CTLR);
> >          }
> > @@ -4784,9 +4777,6 @@ static void its_restore_enable(void)
> >          void __iomem *base;
> >          int i;
> >
> > -        if (!(its->flags & ITS_FLAGS_SAVE_SUSPEND_STATE))
> > -            continue;
> > -
> >          base = its->base;
> >
> >          /*
> > @@ -5074,9 +5064,6 @@ static int __init its_probe_one(struct resource 
> > *res,
> >          ctlr |= GITS_CTLR_ImDe;
> >      writel_relaxed(ctlr, its->base + GITS_CTLR);
> >
> > -    if (GITS_TYPER_HCC(typer))
> > -        its->flags |= ITS_FLAGS_SAVE_SUSPEND_STATE;
> > -
> >      err = its_init_domain(handle, its);
> >      if (err)
> >          goto out_free_tables;
>
> I'm OK with the patch itself, but I don't want to paper over broken 
> firmware.
> I'll get TF-A fixed one way or another, but I want to be sure yours is 
> too.
> If firmware does its job correctly, we shouldn't have to do all of this.
>
>         M.

Thanks

        Xu.