linux-kernel - Re: [PATCH] iommu/mediatek: Fix crash on isr after kexec()

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Message-ID: <CANiDSCv_ZBLFTp42AZz9Td_JCR0MKLooW2gtFo3woT-dOQtm8w@mail.gmail.com>
Date:   Mon, 28 Nov 2022 23:14:37 +0100
From:   Ricardo Ribalda <ribalda@...omium.org>
To:     Yong Wu (吴勇) <Yong.Wu@...iatek.com>
Cc:     "robin.murphy@....com" <robin.murphy@....com>,
        "joro@...tes.org" <joro@...tes.org>,
        "matthias.bgg@...il.com" <matthias.bgg@...il.com>,
        "will@...nel.org" <will@...nel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-mediatek@...ts.infradead.org" 
        <linux-mediatek@...ts.infradead.org>,
        "iommu@...ts.linux.dev" <iommu@...ts.linux.dev>
Subject: Re: [PATCH] iommu/mediatek: Fix crash on isr after kexec()

Hi Yong


On Mon, 28 Nov 2022 at 07:44, Yong Wu (吴勇) <Yong.Wu@...iatek.com> wrote:
>
> On Fri, 2022-11-25 at 17:28 +0100, Ricardo Ribalda wrote:
> > If the system is rebooted via isr(), the IRQ handler might be
> > triggerd
> > before the domain is initialized. Resulting on an invalid memory
> > access
> > error.
> >
> > Fix:
> > [    0.500930] Unable to handle kernel read from unreadable memory at
> > virtual address 0000000000000070
> > [    0.501166] Call trace:
> > [    0.501174]  report_iommu_fault+0x28/0xfc
> > [    0.501180]  mtk_iommu_isr+0x10c/0x1c0
> >
> > Signed-off-by: Ricardo Ribalda <ribalda@...omium.org>
> > ---
> > To: Yong Wu <yong.wu@...iatek.com>
> > To: Joerg Roedel <joro@...tes.org>
> > To: Will Deacon <will@...nel.org>
> > To: Robin Murphy <robin.murphy@....com>
> > To: Matthias Brugger <matthias.bgg@...il.com>
> > Cc: iommu@...ts.linux.dev
> > Cc: linux-mediatek@...ts.infradead.org
> > Cc: linux-arm-kernel@...ts.infradead.org
> > Cc: linux-kernel@...r.kernel.org
> > ---
> >  drivers/iommu/mtk_iommu.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
> > index 2ab2ecfe01f8..17f6be5a5097 100644
> > --- a/drivers/iommu/mtk_iommu.c
> > +++ b/drivers/iommu/mtk_iommu.c
> > @@ -454,7 +454,7 @@ static irqreturn_t mtk_iommu_isr(int irq, void
> > *dev_id)
> >               fault_larb = data->plat_data-
> > >larbid_remap[fault_larb][sub_comm];
> >       }
> >
> > -     if (report_iommu_fault(&dom->domain, bank->parent_dev,
> > fault_iova,
> > +     if (dom && report_iommu_fault(&dom->domain, bank->parent_dev,
> > fault_iova,
>
>
> Which SoC does this issue happen? Does this issue is happened in the
> upstream kernel or the downstream kernel?

I am using chromeos-5.10 and chromeos-5.15 (which are pretty much upstream).

I have seen this issue at least with MT8195 and MT8183


>
> Normally each port enable the iommu defaultly. Let's print the error
> log even though "dom" is null to check which port fail here. then
> analyse the port's behavior.
>
> if (!dom || report_iommu_fault(xx))
>      dev_err_ratelimited(xx)

sending a v2 with the change.

Thanks!


>
> >                              write ? IOMMU_FAULT_WRITE :
> > IOMMU_FAULT_READ)) {
> >               dev_err_ratelimited(
> >                       bank->parent_dev,
> >
> > ---
> > base-commit: 4312098baf37ee17a8350725e6e0d0e8590252d4
> > change-id: 20221125-mtk-iommu-13023f971298
> >
> > Best regards,



-- 
Ricardo Ribalda