linux-kernel - RE: [PATCH v4 04/12] iommu/vt-d: Add 256-bit invalidation descriptor support

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Message-ID: <A2975661238FB949B60364EF0F2C257439D5FAA2@SHSMSX104.ccr.corp.intel.com>
Date:   Wed, 7 Nov 2018 06:07:07 +0000
From:   "Liu, Yi L" <yi.l.liu@...el.com>
To:     Lu Baolu <baolu.lu@...ux.intel.com>,
        Joerg Roedel <joro@...tes.org>,
        "David Woodhouse" <dwmw2@...radead.org>
CC:     "Raj, Ashok" <ashok.raj@...el.com>,
        "Kumar, Sanjay K" <sanjay.k.kumar@...el.com>,
        "Pan, Jacob jun" <jacob.jun.pan@...el.com>,
        "Tian, Kevin" <kevin.tian@...el.com>,
        "Sun, Yi Y" <yi.y.sun@...el.com>,
        "peterx@...hat.com" <peterx@...hat.com>,
        Jean-Philippe Brucker <jean-philippe.brucker@....com>,
        "iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Jacob Pan <jacob.jun.pan@...ux.intel.com>
Subject: RE: [PATCH v4 04/12] iommu/vt-d: Add 256-bit invalidation
 descriptor support

Hi Baolu,

> From: Lu Baolu [mailto:baolu.lu@...ux.intel.com]
> Sent: Monday, November 5, 2018 1:32 PM

[...]

> ---
>  drivers/iommu/dmar.c                | 83 +++++++++++++++++++----------
>  drivers/iommu/intel-svm.c           | 76 ++++++++++++++++----------
>  drivers/iommu/intel_irq_remapping.c |  6 ++-
>  include/linux/intel-iommu.h         |  9 +++-
>  4 files changed, 115 insertions(+), 59 deletions(-)
> 
> diff --git a/drivers/iommu/dmar.c b/drivers/iommu/dmar.c
> index d9c748b6f9e4..ec10427b98ac 100644
> --- a/drivers/iommu/dmar.c
> +++ b/drivers/iommu/dmar.c
> @@ -1160,6 +1160,7 @@ static int qi_check_fault(struct intel_iommu *iommu, int
> index)
>  	int head, tail;
>  	struct q_inval *qi = iommu->qi;
>  	int wait_index = (index + 1) % QI_LENGTH;
> +	int shift = qi_shift(iommu);
> 
>  	if (qi->desc_status[wait_index] == QI_ABORT)
>  		return -EAGAIN;
> @@ -1173,13 +1174,15 @@ static int qi_check_fault(struct intel_iommu *iommu,
> int index)
>  	 */
>  	if (fault & DMA_FSTS_IQE) {
>  		head = readl(iommu->reg + DMAR_IQH_REG);
> -		if ((head >> DMAR_IQ_SHIFT) == index) {
> +		if ((head >> shift) == index) {
> +			struct qi_desc *desc = qi->desc + head;
> +
>  			pr_err("VT-d detected invalid descriptor: "
>  				"low=%llx, high=%llx\n",
> -				(unsigned long long)qi->desc[index].low,
> -				(unsigned long long)qi->desc[index].high);
> -			memcpy(&qi->desc[index], &qi->desc[wait_index],
> -					sizeof(struct qi_desc));
> +				(unsigned long long)desc->qw0,
> +				(unsigned long long)desc->qw1);

Still missing qw2 and qw3. May make the print differ based on if smts is configed.

> +			memcpy(desc, qi->desc + (wait_index << shift),

Would "memcpy(desc, (unsigned long long) (qi->desc +  (wait_index << shift)," be
more safe?

> +			       1 << shift);
>  			writel(DMA_FSTS_IQE, iommu->reg + DMAR_FSTS_REG);
>  			return -EINVAL;
>  		}
> @@ -1191,10 +1194,10 @@ static int qi_check_fault(struct intel_iommu *iommu,
> int index)
>  	 */
>  	if (fault & DMA_FSTS_ITE) {
>  		head = readl(iommu->reg + DMAR_IQH_REG);
> -		head = ((head >> DMAR_IQ_SHIFT) - 1 + QI_LENGTH) % QI_LENGTH;
> +		head = ((head >> shift) - 1 + QI_LENGTH) % QI_LENGTH;
>  		head |= 1;
>  		tail = readl(iommu->reg + DMAR_IQT_REG);
> -		tail = ((tail >> DMAR_IQ_SHIFT) - 1 + QI_LENGTH) % QI_LENGTH;
> +		tail = ((tail >> shift) - 1 + QI_LENGTH) % QI_LENGTH;
> 
>  		writel(DMA_FSTS_ITE, iommu->reg + DMAR_FSTS_REG);
> 
> @@ -1222,15 +1225,14 @@ int qi_submit_sync(struct qi_desc *desc, struct
> intel_iommu *iommu)
>  {
>  	int rc;
>  	struct q_inval *qi = iommu->qi;
> -	struct qi_desc *hw, wait_desc;
> +	int offset, shift, length;
> +	struct qi_desc wait_desc;
>  	int wait_index, index;
>  	unsigned long flags;
> 
>  	if (!qi)
>  		return 0;
> 
> -	hw = qi->desc;
> -
>  restart:
>  	rc = 0;
> 
> @@ -1243,16 +1245,21 @@ int qi_submit_sync(struct qi_desc *desc, struct
> intel_iommu *iommu)
> 
>  	index = qi->free_head;
>  	wait_index = (index + 1) % QI_LENGTH;
> +	shift = qi_shift(iommu);
> +	length = 1 << shift;
> 
>  	qi->desc_status[index] = qi->desc_status[wait_index] = QI_IN_USE;
> 
> -	hw[index] = *desc;
> -
> -	wait_desc.low = QI_IWD_STATUS_DATA(QI_DONE) |
> +	offset = index << shift;
> +	memcpy(qi->desc + offset, desc, length);
> +	wait_desc.qw0 = QI_IWD_STATUS_DATA(QI_DONE) |
>  			QI_IWD_STATUS_WRITE | QI_IWD_TYPE;
> -	wait_desc.high = virt_to_phys(&qi->desc_status[wait_index]);
> +	wait_desc.qw1 = virt_to_phys(&qi->desc_status[wait_index]);
> +	wait_desc.qw2 = 0;
> +	wait_desc.qw3 = 0;
> 
> -	hw[wait_index] = wait_desc;
> +	offset = wait_index << shift;
> +	memcpy(qi->desc + offset, &wait_desc, length);

same question with above one.

Thanks,
Yi Liu