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Subject: Re: [PATCH v2 0/7] iommu/dma-iommu: Split iommu_dma_map_msi_msg in
 two parts
To:     Julien Grall <julien.grall@arm.com>, linux-kernel@vger.kernel.org,
        iommu@lists.linux-foundation.org
Cc:     logang@deltatee.com, douliyangs@gmail.com,
        miquel.raynal@bootlin.com, jason@lakedaemon.net,
        tglx@linutronix.de, joro@8bytes.org, robin.murphy@arm.com,
        bigeasy@linutronix.de, linux-rt-users@vger.kernel.org
References: <20190429144428.29254-1-julien.grall@arm.com>
From:   Marc Zyngier <marc.zyngier@arm.com>
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Organization: ARM Ltd
Message-ID: <646d035d-e160-a19d-8c3a-e1935cf691b5@arm.com>
Date:   Mon, 29 Apr 2019 16:57:20 +0100
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In-Reply-To: <20190429144428.29254-1-julien.grall@arm.com>
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Sender: linux-kernel-owner@vger.kernel.org
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Hi Julien,

On 29/04/2019 15:44, Julien Grall wrote:
> Hi all,
> 
> On RT, the function iommu_dma_map_msi_msg expects to be called from preemptible
> context. However, this is not always the case resulting a splat with
> !CONFIG_DEBUG_ATOMIC_SLEEP:
> 
> [   48.875777] BUG: sleeping function called from invalid context at kernel/locking/rtmutex.c:974
> [   48.875779] in_atomic(): 1, irqs_disabled(): 128, pid: 2103, name: ip
> [   48.875782] INFO: lockdep is turned off.
> [   48.875784] irq event stamp: 10684
> [   48.875786] hardirqs last  enabled at (10683): [<ffff0000110c8d70>] _raw_spin_unlock_irqrestore+0x88/0x90
> [   48.875791] hardirqs last disabled at (10684): [<ffff0000110c8b2c>] _raw_spin_lock_irqsave+0x24/0x68
> [   48.875796] softirqs last  enabled at (0): [<ffff0000100ec590>] copy_process.isra.1.part.2+0x8d8/0x1970
> [   48.875801] softirqs last disabled at (0): [<0000000000000000>]           (null)
> [   48.875805] Preemption disabled at:
> [   48.875805] [<ffff000010189ae8>] __setup_irq+0xd8/0x6c0
> [   48.875811] CPU: 2 PID: 2103 Comm: ip Not tainted 5.0.3-rt1-00007-g42ede9a0fed6 #45
> [   48.875815] Hardware name: ARM LTD ARM Juno Development Platform/ARM Juno Development Platform, BIOS EDK II Jan 23 2017
> [   48.875817] Call trace:
> [   48.875818]  dump_backtrace+0x0/0x140
> [   48.875821]  show_stack+0x14/0x20
> [   48.875823]  dump_stack+0xa0/0xd4
> [   48.875827]  ___might_sleep+0x16c/0x1f8
> [   48.875831]  rt_spin_lock+0x5c/0x70
> [   48.875835]  iommu_dma_map_msi_msg+0x5c/0x1d8
> [   48.875839]  gicv2m_compose_msi_msg+0x3c/0x48
> [   48.875843]  irq_chip_compose_msi_msg+0x40/0x58
> [   48.875846]  msi_domain_activate+0x38/0x98
> [   48.875849]  __irq_domain_activate_irq+0x58/0xa0
> [   48.875852]  irq_domain_activate_irq+0x34/0x58
> [   48.875855]  irq_activate+0x28/0x30
> [   48.875858]  __setup_irq+0x2b0/0x6c0
> [   48.875861]  request_threaded_irq+0xdc/0x188
> [   48.875865]  sky2_setup_irq+0x44/0xf8
> [   48.875868]  sky2_open+0x1a4/0x240
> [   48.875871]  __dev_open+0xd8/0x188
> [   48.875874]  __dev_change_flags+0x164/0x1f0
> [   48.875877]  dev_change_flags+0x20/0x60
> [   48.875879]  do_setlink+0x2a0/0xd30
> [   48.875882]  __rtnl_newlink+0x5b4/0x6d8
> [   48.875885]  rtnl_newlink+0x50/0x78
> [   48.875888]  rtnetlink_rcv_msg+0x178/0x640
> [   48.875891]  netlink_rcv_skb+0x58/0x118
> [   48.875893]  rtnetlink_rcv+0x14/0x20
> [   48.875896]  netlink_unicast+0x188/0x200
> [   48.875898]  netlink_sendmsg+0x248/0x3d8
> [   48.875900]  sock_sendmsg+0x18/0x40
> [   48.875904]  ___sys_sendmsg+0x294/0x2d0
> [   48.875908]  __sys_sendmsg+0x68/0xb8
> [   48.875911]  __arm64_sys_sendmsg+0x20/0x28
> [   48.875914]  el0_svc_common+0x90/0x118
> [   48.875918]  el0_svc_handler+0x2c/0x80
> [   48.875922]  el0_svc+0x8/0xc
> 
> This series is a first attempt to rework how MSI are mapped and composed
> when an IOMMU is present.
> 
> I was able to test the changes in GICv2m and GICv3 ITS. I don't have
> hardware for the other interrupt controllers.
> 
> Cheers,
> 
> Julien Grall (7):
>   genirq/msi: Add a new field in msi_desc to store an IOMMU cookie
>   iommu/dma-iommu: Split iommu_dma_map_msi_msg() in two parts
>   irqchip/gicv2m: Don't map the MSI page in gicv2m_compose_msi_msg()
>   irqchip/gic-v3-its: Don't map the MSI page in
>     its_irq_compose_msi_msg()
>   irqchip/ls-scfg-msi: Don't map the MSI page in
>     ls_scfg_msi_compose_msg()
>   irqchip/gic-v3-mbi: Don't map the MSI page in mbi_compose_m{b,
>     s}i_msg()
>   iommu/dma-iommu: Remove iommu_dma_map_msi_msg()
> 
>  drivers/iommu/Kconfig             |  1 +
>  drivers/iommu/dma-iommu.c         | 49 +++++++++++++++++++++++----------------
>  drivers/irqchip/irq-gic-v2m.c     |  8 ++++++-
>  drivers/irqchip/irq-gic-v3-its.c  |  5 +++-
>  drivers/irqchip/irq-gic-v3-mbi.c  | 15 ++++++++++--
>  drivers/irqchip/irq-ls-scfg-msi.c |  7 +++++-
>  include/linux/dma-iommu.h         | 22 ++++++++++++++++--
>  include/linux/msi.h               | 26 +++++++++++++++++++++
>  kernel/irq/Kconfig                |  3 +++
>  9 files changed, 109 insertions(+), 27 deletions(-)

Thanks for having reworked this. I'm quite happy with the way this looks
now (modulo the couple of nits Robin and I mentioned, which I'm to
address myself).

Jorg: are you OK with this going via the irq tree?

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...