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From: Lu Baolu <baolu.lu@linux.intel.com>
To: Dmitry Safonov <dima@arista.com>,
	linux-kernel@vger.kernel.org, joro@8bytes.org, "Raj,
	Ashok" <ashok.raj@intel.com>
Cc: 0x7f454c46@gmail.com,
	Alex Williamson <alex.williamson@redhat.com>,
	David Woodhouse <dwmw2@infradead.org>,
	Ingo Molnar <mingo@kernel.org>,
	iommu@lists.linux-foundation.org
Subject: Re: [PATCHv4 2/2] iommu/vt-d: Limit number of faults to clear in irq handler
Date: Wed, 2 May 2018 14:34:39 +0800	[thread overview]
Message-ID: <5AE95BFF.5040306@linux.intel.com> (raw)
In-Reply-To: <20180331003312.6390-2-dima@arista.com>

Hi,

On 03/31/2018 08:33 AM, Dmitry Safonov wrote:
> Theoretically, on some machines faults might be generated faster than
> they're cleared by CPU.

Is this a real case?

>  Let's limit the cleaning-loop by number of hw
> fault registers.

Will this cause the fault recording registers full of faults, hence new
faults will be dropped without logging? And even worse, new faults
will not generate interrupts?

Best regards,
Lu Baolu

>
> Cc: Alex Williamson <alex.williamson@redhat.com>
> Cc: David Woodhouse <dwmw2@infradead.org>
> Cc: Ingo Molnar <mingo@kernel.org>
> Cc: Joerg Roedel <joro@8bytes.org>
> Cc: Lu Baolu <baolu.lu@linux.intel.com>
> Cc: iommu@lists.linux-foundation.org
> Signed-off-by: Dmitry Safonov <dima@arista.com>
> ---
>  drivers/iommu/dmar.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/iommu/dmar.c b/drivers/iommu/dmar.c
> index 6c4ea32ee6a9..cf1105111209 100644
> --- a/drivers/iommu/dmar.c
> +++ b/drivers/iommu/dmar.c
> @@ -1615,7 +1615,7 @@ static int dmar_fault_do_one(struct intel_iommu *iommu, int type,
>  irqreturn_t dmar_fault(int irq, void *dev_id)
>  {
>  	struct intel_iommu *iommu = dev_id;
> -	int reg, fault_index;
> +	int reg, fault_index, i;
>  	u32 fault_status;
>  	unsigned long flag;
>  	static DEFINE_RATELIMIT_STATE(rs,
> @@ -1633,7 +1633,7 @@ irqreturn_t dmar_fault(int irq, void *dev_id)
>  
>  	fault_index = dma_fsts_fault_record_index(fault_status);
>  	reg = cap_fault_reg_offset(iommu->cap);
> -	while (1) {
> +	for (i = 0; i < cap_num_fault_regs(iommu->cap); i++) {
>  		/* Disable printing, simply clear the fault when ratelimited */
>  		bool ratelimited = !__ratelimit(&rs);
>  		u8 fault_reason;

  reply	other threads:[~2018-05-02  6:34 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-31  0:33 [PATCHv4 1/2] iommu/vt-d: Ratelimit each dmar fault printing Dmitry Safonov
2018-03-31  0:33 ` [PATCHv4 2/2] iommu/vt-d: Limit number of faults to clear in irq handler Dmitry Safonov
2018-05-02  6:34   ` Lu Baolu [this message]
2018-05-02 12:38     ` Dmitry Safonov
2018-05-02 23:49       ` Lu Baolu
2018-05-03  0:52         ` Dmitry Safonov
2018-05-03  1:32           ` Lu Baolu
2018-05-03  1:59             ` Dmitry Safonov
2018-05-03  2:16               ` Lu Baolu
2018-05-03  2:32                 ` Lu Baolu
2018-05-03  2:34                 ` Dmitry Safonov
2018-05-03  2:44                   ` Lu Baolu
2018-05-02  2:22 ` [PATCHv4 1/2] iommu/vt-d: Ratelimit each dmar fault printing Dmitry Safonov
2018-05-03 12:40   ` Joerg Roedel
2018-05-03 16:12     ` Dmitry Safonov

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