From: Tianyu Lan <ltykernel@gmail.com>
To: Long Li <longli@microsoft.com>, KY Srinivasan <kys@microsoft.com>,
Haiyang Zhang <haiyangz@microsoft.com>,
Stephen Hemminger <sthemmin@microsoft.com>,
"wei.liu@kernel.org" <wei.liu@kernel.org>,
Dexuan Cui <decui@microsoft.com>,
"tglx@linutronix.de" <tglx@linutronix.de>,
"mingo@redhat.com" <mingo@redhat.com>,
"bp@alien8.de" <bp@alien8.de>,
"dave.hansen@linux.intel.com" <dave.hansen@linux.intel.com>,
"x86@kernel.org" <x86@kernel.org>,
"hpa@zytor.com" <hpa@zytor.com>,
"davem@davemloft.net" <davem@davemloft.net>,
"kuba@kernel.org" <kuba@kernel.org>,
"jejb@linux.ibm.com" <jejb@linux.ibm.com>,
"martin.petersen@oracle.com" <martin.petersen@oracle.com>,
"arnd@arndb.de" <arnd@arndb.de>,
"hch@infradead.org" <hch@infradead.org>,
"m.szyprowski@samsung.com" <m.szyprowski@samsung.com>,
"robin.murphy@arm.com" <robin.murphy@arm.com>,
Tianyu Lan <Tianyu.Lan@microsoft.com>,
"thomas.lendacky@amd.com" <thomas.lendacky@amd.com>,
"Michael Kelley (LINUX)" <mikelley@microsoft.com>
Cc: "iommu@lists.linux-foundation.org"
<iommu@lists.linux-foundation.org>,
"linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>,
"linux-hyperv@vger.kernel.org" <linux-hyperv@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
vkuznets <vkuznets@redhat.com>,
"brijesh.singh@amd.com" <brijesh.singh@amd.com>,
"konrad.wilk@oracle.com" <konrad.wilk@oracle.com>,
"hch@lst.de" <hch@lst.de>, "joro@8bytes.org" <joro@8bytes.org>,
"parri.andrea@gmail.com" <parri.andrea@gmail.com>,
"dave.hansen@intel.com" <dave.hansen@intel.com>
Subject: Re: [PATCH V6 4/5] scsi: storvsc: Add Isolation VM support for storvsc driver
Date: Thu, 9 Dec 2021 19:17:08 +0800 [thread overview]
Message-ID: <ff4497cc-741a-113c-c6eb-dd5966716863@gmail.com> (raw)
In-Reply-To: <BY5PR21MB1506535EF9222ED4300C38BBCE709@BY5PR21MB1506.namprd21.prod.outlook.com>
On 12/9/2021 4:00 PM, Long Li wrote:
>> @@ -1848,21 +1851,22 @@ static int storvsc_queuecommand(struct Scsi_Host
>> *host, struct scsi_cmnd *scmnd)
>> payload->range.len = length;
>> payload->range.offset = offset_in_hvpg;
>>
>> + sg_count = scsi_dma_map(scmnd);
>> + if (sg_count < 0)
>> + return SCSI_MLQUEUE_DEVICE_BUSY;
> Hi Tianyu,
>
> This patch (and this patch series) unconditionally adds code for dealing with DMA addresses for all VMs, including non-isolation VMs.
>
> Does this add performance penalty for VMs that don't require isolation?
>
Hi Long:
scsi_dma_map() in the traditional VM just save sg->offset to
sg->dma_address and no data copy because swiotlb bounce buffer code
doesn't work. The data copy only takes place in the Isolation VM and
swiotlb_force is set. So there is no additional overhead in the
traditional VM.
Thanks.
next prev parent reply other threads:[~2021-12-09 11:17 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-07 7:55 [PATCH V6 0/5] x86/Hyper-V: Add Hyper-V Isolation VM support(Second part) Tianyu Lan
2021-12-07 7:55 ` [PATCH V6 1/5] swiotlb: Add swiotlb bounce buffer remap function for HV IVM Tianyu Lan
2021-12-07 7:55 ` [PATCH V6 2/5] x86/hyper-v: Add hyperv Isolation VM check in the cc_platform_has() Tianyu Lan
2021-12-07 9:47 ` Borislav Petkov
2021-12-07 11:18 ` Tianyu Lan
2021-12-08 14:52 ` [PATCH V6.1] " Tianyu Lan
2021-12-08 15:12 ` Tianyu Lan
2021-12-09 20:38 ` [PATCH V6 2/5] " Michael Kelley (LINUX)
2021-12-10 11:26 ` Tianyu Lan
2021-12-07 7:55 ` [PATCH V6 3/5] hyper-v: Enable swiotlb bounce buffer for Isolation VM Tianyu Lan
2021-12-09 20:09 ` Michael Kelley (LINUX)
2021-12-10 13:25 ` Tianyu Lan
2021-12-10 14:01 ` Tianyu Lan
2021-12-07 7:56 ` [PATCH V6 4/5] scsi: storvsc: Add Isolation VM support for storvsc driver Tianyu Lan
2021-12-09 8:00 ` Long Li
2021-12-09 11:17 ` Tianyu Lan [this message]
2021-12-07 7:56 ` [PATCH V6 5/5] net: netvsc: Add Isolation VM support for netvsc driver Tianyu Lan
2021-12-08 20:14 ` Haiyang Zhang
2021-12-09 8:08 ` Tianyu Lan
2021-12-09 19:54 ` Michael Kelley (LINUX)
2021-12-09 20:40 ` Haiyang Zhang
-- strict thread matches above, loose matches on Subject: below --
2021-12-07 7:19 [PATCH V6 0/5] x86/Hyper-V: Add Hyper-V Isolation VM support(Second part) Tianyu Lan
2021-12-07 7:19 ` [PATCH V6 4/5] scsi: storvsc: Add Isolation VM support for storvsc driver Tianyu Lan
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