From: Dave Hansen <dave.hansen@intel•com>
To: Tianyu Lan <ltykernel@gmail•com>,
kys@microsoft•com, haiyangz@microsoft•com,
sthemmin@microsoft•com, wei.liu@kernel•org, decui@microsoft•com,
tglx@linutronix•de, mingo@redhat•com, bp@alien8•de,
x86@kernel•org, hpa@zytor•com, dave.hansen@linux•intel.com,
luto@kernel•org, peterz@infradead•org, konrad.wilk@oracle•com,
boris.ostrovsky@oracle•com, jgross@suse•com,
sstabellini@kernel•org, joro@8bytes•org, will@kernel•org,
davem@davemloft•net, kuba@kernel•org, jejb@linux•ibm.com,
martin.petersen@oracle•com, arnd@arndb•de, hch@lst•de,
m.szyprowski@samsung•com, robin.murphy@arm•com,
thomas.lendacky@amd•com, brijesh.singh@amd•com, ardb@kernel•org,
Tianyu.Lan@microsoft•com, rientjes@google•com,
martin.b.radev@gmail•com, akpm@linux-foundation•org,
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aneesh.kumar@linux•ibm.com, krish.sadhukhan@oracle•com,
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hannes@cmpxchg•org, sfr@canb•auug.org.au,
michael.h.kelley@microsoft•com
Cc: iommu@lists•linux-foundation.org, linux-arch@vger•kernel.org,
linux-hyperv@vger•kernel.org, linux-kernel@vger•kernel.org,
linux-scsi@vger•kernel.org, netdev@vger•kernel.org,
vkuznets@redhat•com, anparri@microsoft•com
Subject: Re: [PATCH 03/13] x86/HV: Add new hvcall guest address host visibility support
Date: Thu, 29 Jul 2021 07:09:55 -0700 [thread overview]
Message-ID: <ec1d4cfd-bbbc-e27a-7589-e85d9f0438f4@intel.com> (raw)
In-Reply-To: <0d956a05-7d24-57a0-f4a9-dccc849b52fc@gmail.com>
On 7/29/21 6:01 AM, Tianyu Lan wrote:
> On 7/29/2021 1:06 AM, Dave Hansen wrote:
>> On 7/28/21 7:52 AM, Tianyu Lan wrote:
>>> @@ -1986,7 +1988,9 @@ static int __set_memory_enc_dec(unsigned long
>>> addr, int numpages, bool enc)
>>> int ret;
>>> /* Nothing to do if memory encryption is not active */
>>> - if (!mem_encrypt_active())
>>> + if (hv_is_isolation_supported())
>>> + return hv_set_mem_enc(addr, numpages, enc);
>>> + else if (!mem_encrypt_active())
>>> return 0;
>>
>> One more thing. If you're going to be patching generic code, please
>> start using feature checks that can get optimized away at runtime.
>> hv_is_isolation_supported() doesn't look like the world's cheapest
>> check. It can't be inlined and costs at least a function call.
>
> Yes, you are right. How about adding a static branch key for the check
> of isolation VM? This may reduce the check cost.
I don't think you need a static key.
There are basically three choices:
1. Use an existing X86_FEATURE bit. I think there's already one for
when you are running under a hypervisor. It's not super precise,
but it's better than what you have.
2. Define a new X86_FEATURE bit for when you are running under
Hyper-V.
3. Define a new X86_FEATURE bit specifically for Hyper-V isolation VM
support. This particular feature might be a little uncommon to
deserve its own bit.
I'd probably just do #2.
next prev parent reply other threads:[~2021-07-29 14:12 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-28 14:52 [PATCH 00/13] x86/Hyper-V: Add Hyper-V Isolation VM support Tianyu Lan
2021-07-28 14:52 ` [PATCH 01/13] x86/HV: Initialize GHCB page in Isolation VM Tianyu Lan
2021-08-02 11:53 ` Joerg Roedel
2021-08-02 12:35 ` Tianyu Lan
2021-07-28 14:52 ` [PATCH 02/13] x86/HV: Initialize shared memory boundary in the " Tianyu Lan
2021-07-28 14:52 ` [PATCH 03/13] x86/HV: Add new hvcall guest address host visibility support Tianyu Lan
2021-07-28 15:29 ` Dave Hansen
2021-07-29 12:49 ` Tianyu Lan
2021-08-02 12:01 ` Joerg Roedel
2021-08-02 12:59 ` Tianyu Lan
2021-08-02 13:11 ` Juergen Gross
2021-08-02 13:30 ` Joerg Roedel
2021-07-28 17:06 ` Dave Hansen
2021-07-29 13:01 ` Tianyu Lan
2021-07-29 14:09 ` Dave Hansen [this message]
2021-07-29 15:02 ` Tianyu Lan
2021-07-29 16:05 ` Dave Hansen
2021-07-30 2:52 ` Tianyu Lan
2021-07-28 14:52 ` [PATCH 04/13] HV: Mark vmbus ring buffer visible to host in Isolation VM Tianyu Lan
2021-08-02 12:07 ` Joerg Roedel
2021-08-02 12:56 ` Tianyu Lan
2021-08-02 12:59 ` Joerg Roedel
2021-08-02 13:08 ` Tianyu Lan
2021-07-28 14:52 ` [PATCH 05/13] HV: Add Write/Read MSR registers via ghcb page Tianyu Lan
2021-08-02 12:28 ` Joerg Roedel
2021-08-02 13:18 ` Tianyu Lan
2021-07-28 14:52 ` [PATCH 06/13] HV: Add ghcb hvcall support for SNP VM Tianyu Lan
2021-08-02 12:39 ` Joerg Roedel
2021-08-02 13:32 ` Tianyu Lan
2021-07-28 14:52 ` [PATCH 07/13] HV/Vmbus: Add SNP support for VMbus channel initiate message Tianyu Lan
2021-08-02 12:58 ` Joerg Roedel
2021-07-28 14:52 ` [PATCH 08/13] HV/Vmbus: Initialize VMbus ring buffer for Isolation VM Tianyu Lan
2021-07-28 14:52 ` [PATCH 09/13] DMA: Add dma_map_decrypted/dma_unmap_encrypted() function Tianyu Lan
2021-07-29 15:13 ` Tianyu Lan
2021-07-28 14:52 ` [PATCH 10/13] x86/Swiotlb: Add Swiotlb bounce buffer remap function for HV IVM Tianyu Lan
2021-07-29 16:29 ` Konrad Rzeszutek Wilk
2021-07-30 4:10 ` Tianyu Lan
2021-07-28 14:52 ` [PATCH 11/13] HV/IOMMU: Enable swiotlb bounce buffer for Isolation VM Tianyu Lan
2021-07-28 14:52 ` [PATCH 12/13] HV/Netvsc: Add Isolation VM support for netvsc driver Tianyu Lan
2021-07-28 14:52 ` [PATCH 13/13] HV/Storvsc: Add Isolation VM support for storvsc driver Tianyu Lan
2021-08-02 13:20 ` Joerg Roedel
2021-08-02 14:08 ` Tianyu Lan
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