Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
From:   jsnitsel@redhat.com
Date:   Mon, 22 May 2023 17:17:13 -0700
To:     Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Cc:     linux-kernel@vger.kernel.org, iommu@lists.linux.dev,
        joro@8bytes.org, joao.m.martins@oracle.com,
        alejandro.j.jimenez@oracle.com, boris.ostrovsky@oracle.com,
        jon.grimm@amd.com, santosh.shukla@amd.com, vasant.hegde@amd.com,
        kishon.vijayabraham@amd.com
Subject: Re: [PATCH v2 4/5] iommu/amd: Do not Invalidate IRT when disable
 IRTE caching
Message-ID: <byrqmwgki5ak5yn74ubvgikeb7ibrzml2lcnnx3qgkyi2omn3x@qyo5q5atbe33>
\From:  Jerry Snitselaar <jsnitsel@redhat.com>
References: <20230519005529.28171-1-suravee.suthikulpanit@amd.com>
 <20230519005529.28171-5-suravee.suthikulpanit@amd.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20230519005529.28171-5-suravee.suthikulpanit@amd.com>
X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH,
        DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_NONE,
        RCVD_IN_MSPIKE_H2,SPF_HELO_NONE,SPF_NONE,T_SCC_BODY_TEXT_LINE
        autolearn=ham autolearn_force=no version=3.4.6
X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on
        lindbergh.monkeyblade.net
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Thu, May 18, 2023 at 08:55:28PM -0400, Suravee Suthikulpanit wrote:
> With the Interrupt Remapping Table cache disabled, there is no need to
> issue invalidate IRT and wait for its completion. Therefore, add logic
> to bypass the operation.
> 
> Suggested-by: Joao Martins <joao.m.martins@oracle.com>
> Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>

Would it be clearer for the summary to be "iommu/amd: Do not
Invalidate IRT when IRTE caching is disabled"?

Reviewed-by: Jerry Snitselaar <jsnitsel@redhat.com>

> ---
>  drivers/iommu/amd/iommu.c | 21 +++++++++++++++------
>  1 file changed, 15 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
> index 0c4a2796bb0a..51c2b018433d 100644
> --- a/drivers/iommu/amd/iommu.c
> +++ b/drivers/iommu/amd/iommu.c
> @@ -1273,12 +1273,24 @@ static void amd_iommu_flush_irt_all(struct amd_iommu *iommu)
>  	u32 devid;
>  	u16 last_bdf = iommu->pci_seg->last_bdf;
>  
> +	if (iommu->irtcachedis_enabled)
> +		return;
> +
>  	for (devid = 0; devid <= last_bdf; devid++)
>  		iommu_flush_irt(iommu, devid);
>  
>  	iommu_completion_wait(iommu);
>  }
>  
> +static void iommu_flush_irt_and_complete(struct amd_iommu *iommu, u16 devid)
> +{
> +	if (iommu->irtcachedis_enabled)
> +		return;
> +
> +	iommu_flush_irt(iommu, devid);
> +	iommu_completion_wait(iommu);
> +}
> +
>  void iommu_flush_all_caches(struct amd_iommu *iommu)
>  {
>  	if (iommu_feature(iommu, FEATURE_IA)) {
> @@ -3028,8 +3040,7 @@ static int modify_irte_ga(struct amd_iommu *iommu, u16 devid, int index,
>  
>  	raw_spin_unlock_irqrestore(&table->lock, flags);
>  
> -	iommu_flush_irt(iommu, devid);
> -	iommu_completion_wait(iommu);
> +	iommu_flush_irt_and_complete(iommu, devid);
>  
>  	return 0;
>  }
> @@ -3048,8 +3059,7 @@ static int modify_irte(struct amd_iommu *iommu,
>  	table->table[index] = irte->val;
>  	raw_spin_unlock_irqrestore(&table->lock, flags);
>  
> -	iommu_flush_irt(iommu, devid);
> -	iommu_completion_wait(iommu);
> +	iommu_flush_irt_and_complete(iommu, devid);
>  
>  	return 0;
>  }
> @@ -3067,8 +3077,7 @@ static void free_irte(struct amd_iommu *iommu, u16 devid, int index)
>  	iommu->irte_ops->clear_allocated(table, index);
>  	raw_spin_unlock_irqrestore(&table->lock, flags);
>  
> -	iommu_flush_irt(iommu, devid);
> -	iommu_completion_wait(iommu);
> +	iommu_flush_irt_and_complete(iommu, devid);
>  }
>  
>  static void irte_prepare(void *entry,
> -- 
> 2.31.1
>