linux-kernel - Re: [PATCH V9 07/10] iommu/vt-d: Cache virtual command capability register

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Message-ID: <5776bf45-7541-1576-9ced-38883447bf29@redhat.com>
Date:   Wed, 12 Feb 2020 14:00:22 +0100
From:   Auger Eric <eric.auger@...hat.com>
To:     Jacob Pan <jacob.jun.pan@...ux.intel.com>,
        iommu@...ts.linux-foundation.org,
        LKML <linux-kernel@...r.kernel.org>,
        Lu Baolu <baolu.lu@...ux.intel.com>,
        Joerg Roedel <joro@...tes.org>,
        David Woodhouse <dwmw2@...radead.org>
Cc:     Yi Liu <yi.l.liu@...el.com>, "Tian, Kevin" <kevin.tian@...el.com>,
        Raj Ashok <ashok.raj@...el.com>,
        Alex Williamson <alex.williamson@...hat.com>,
        Christoph Hellwig <hch@...radead.org>,
        Jean-Philippe Brucker <jean-philippe@...aro.com>,
        Jonathan Cameron <jic23@...nel.org>
Subject: Re: [PATCH V9 07/10] iommu/vt-d: Cache virtual command capability
 register

Hi Jacob,

On 1/29/20 7:01 AM, Jacob Pan wrote:
> Virtual command registers are used in the guest only, to prevent
> vmexit cost, we cache the capability and store it during initialization.
> 
> Signed-off-by: Jacob Pan <jacob.jun.pan@...ux.intel.com>
I sent my R-b in https://lkml.org/lkml/2019/11/8/228
Also Baolo did. Do I miss any change?

Again history log would help.

Thanks

Eric
> ---
>  drivers/iommu/dmar.c        | 1 +
>  include/linux/intel-iommu.h | 5 +++++
>  2 files changed, 6 insertions(+)
> 
> diff --git a/drivers/iommu/dmar.c b/drivers/iommu/dmar.c
> index 206733ec8140..fd35e625f315 100644
> --- a/drivers/iommu/dmar.c
> +++ b/drivers/iommu/dmar.c
> @@ -953,6 +953,7 @@ static int map_iommu(struct intel_iommu *iommu, u64 phys_addr)
>  		warn_invalid_dmar(phys_addr, " returns all ones");
>  		goto unmap;
>  	}
> +	iommu->vccap = dmar_readq(iommu->reg + DMAR_VCCAP_REG);
>  
>  	/* the registers might be more than one page */
>  	map_size = max_t(int, ecap_max_iotlb_offset(iommu->ecap),
> diff --git a/include/linux/intel-iommu.h b/include/linux/intel-iommu.h
> index dd9fa61689bc..4a8bf3b11de6 100644
> --- a/include/linux/intel-iommu.h
> +++ b/include/linux/intel-iommu.h
> @@ -192,6 +192,9 @@
>  #define ecap_max_handle_mask(e) ((e >> 20) & 0xf)
>  #define ecap_sc_support(e)	((e >> 7) & 0x1) /* Snooping Control */
>  
> +/* Virtual command interface capabilities */
> +#define vccap_pasid(v)		((v & DMA_VCS_PAS)) /* PASID allocation */
> +
>  /* IOTLB_REG */
>  #define DMA_TLB_FLUSH_GRANU_OFFSET  60
>  #define DMA_TLB_GLOBAL_FLUSH (((u64)1) << 60)
> @@ -285,6 +288,7 @@
>  
>  /* PRS_REG */
>  #define DMA_PRS_PPR	((u32)1)
> +#define DMA_VCS_PAS	((u64)1)
>  
>  #define IOMMU_WAIT_OP(iommu, offset, op, cond, sts)			\
>  do {									\
> @@ -535,6 +539,7 @@ struct intel_iommu {
>  	u64		reg_size; /* size of hw register set */
>  	u64		cap;
>  	u64		ecap;
> +	u64		vccap;
>  	u32		gcmd; /* Holds TE, EAFL. Don't need SRTP, SFL, WBF */
>  	raw_spinlock_t	register_lock; /* protect register handling */
>  	int		seq_id;	/* sequence id of the iommu */
>