From: Dave Hansen <dave.hansen@intel.com>
To: Peter Zijlstra <peterz@infradead.org>, Tianyu Lan <ltykernel@gmail.com>
Cc: 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, 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,
Tianyu.Lan@microsoft.com, rppt@kernel.org,
kirill.shutemov@linux.intel.com, akpm@linux-foundation.org,
brijesh.singh@amd.com, thomas.lendacky@amd.com,
pgonda@google.com, david@redhat.com, krish.sadhukhan@oracle.com,
saravanand@fb.com, aneesh.kumar@linux.ibm.com,
xen-devel@lists.xenproject.org, martin.b.radev@gmail.com,
ardb@kernel.org, rientjes@google.com, tj@kernel.org,
keescook@chromium.org, michael.h.kelley@microsoft.com,
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, parri.andrea@gmail.com
Subject: Re: [PATCH V2 03/14] x86/set_memory: Add x86_set_memory_enc static call support
Date: Thu, 5 Aug 2021 07:29:28 -0700 [thread overview]
Message-ID: <fa63e6ad-9536-d5e9-d754-fa04fad69252@intel.com> (raw)
In-Reply-To: <YQv0bRBUq1N5+jgG@hirez.programming.kicks-ass.net>
On 8/5/21 7:23 AM, Peter Zijlstra wrote:
> This is assuming any of this is actually performance critical, based off
> of this using static_call() to begin with.
This code is not performance critical.
I think I sent folks off on a wild goose chase when I asked that we make
an effort to optimize code that does:
if (some_hyperv_check())
foo();
if (some_amd_feature_check())
bar();
with checks that will actually compile away when Hyper-V or
some_amd_feature() is disabled. That's less about performance and just
about good hygiene. I *wanted* to see
cpu_feature_enabled(X86_FEATURE...) checks.
Someone suggested using static calls, and off we went...
Could we please just use cpu_feature_enabled()?
WARNING: multiple messages have this Message-ID (diff)
From: Dave Hansen <dave.hansen@intel.com>
To: Peter Zijlstra <peterz@infradead.org>, Tianyu Lan <ltykernel@gmail.com>
Cc: parri.andrea@gmail.com, linux-hyperv@vger.kernel.org,
brijesh.singh@amd.com, david@redhat.com, ardb@kernel.org,
dave.hansen@linux.intel.com, hpa@zytor.com, kys@microsoft.com,
will@kernel.org, boris.ostrovsky@oracle.com,
linux-arch@vger.kernel.org, wei.liu@kernel.org,
sstabellini@kernel.org, sthemmin@microsoft.com,
xen-devel@lists.xenproject.org, linux-scsi@vger.kernel.org,
aneesh.kumar@linux.ibm.com, x86@kernel.org, decui@microsoft.com,
hch@lst.de, michael.h.kelley@microsoft.com, mingo@redhat.com,
pgonda@google.com, rientjes@google.com, kuba@kernel.org,
jejb@linux.ibm.com, martin.b.radev@gmail.com,
thomas.lendacky@amd.com, Tianyu.Lan@microsoft.com,
keescook@chromium.org, arnd@arndb.de, konrad.wilk@oracle.com,
haiyangz@microsoft.com, bp@alien8.de, luto@kernel.org,
krish.sadhukhan@oracle.com, tglx@linutronix.de,
vkuznets@redhat.com, jgross@suse.com, martin.petersen@oracle.com,
saravanand@fb.com, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org,
kirill.shutemov@linux.intel.com, tj@kernel.org,
akpm@linux-foundation.org, robin.murphy@arm.com,
davem@davemloft.net, rppt@kernel.org
Subject: Re: [PATCH V2 03/14] x86/set_memory: Add x86_set_memory_enc static call support
Date: Thu, 5 Aug 2021 07:29:28 -0700 [thread overview]
Message-ID: <fa63e6ad-9536-d5e9-d754-fa04fad69252@intel.com> (raw)
In-Reply-To: <YQv0bRBUq1N5+jgG@hirez.programming.kicks-ass.net>
On 8/5/21 7:23 AM, Peter Zijlstra wrote:
> This is assuming any of this is actually performance critical, based off
> of this using static_call() to begin with.
This code is not performance critical.
I think I sent folks off on a wild goose chase when I asked that we make
an effort to optimize code that does:
if (some_hyperv_check())
foo();
if (some_amd_feature_check())
bar();
with checks that will actually compile away when Hyper-V or
some_amd_feature() is disabled. That's less about performance and just
about good hygiene. I *wanted* to see
cpu_feature_enabled(X86_FEATURE...) checks.
Someone suggested using static calls, and off we went...
Could we please just use cpu_feature_enabled()?
_______________________________________________
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iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu
next prev parent reply other threads:[~2021-08-05 14:29 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-04 18:44 [PATCH V2 00/14] x86/Hyper-V: Add Hyper-V Isolation VM support Tianyu Lan
2021-08-04 18:44 ` Tianyu Lan
2021-08-04 18:44 ` [PATCH V2 01/14] x86/HV: Initialize GHCB page in Isolation VM Tianyu Lan
2021-08-04 18:44 ` Tianyu Lan
2021-08-04 18:44 ` [PATCH V2 02/14] x86/HV: Initialize shared memory boundary in the " Tianyu Lan
2021-08-04 18:44 ` Tianyu Lan
2021-08-04 18:44 ` [PATCH V2 03/14] x86/set_memory: Add x86_set_memory_enc static call support Tianyu Lan
2021-08-04 18:44 ` Tianyu Lan
2021-08-04 19:27 ` Dave Hansen
2021-08-04 19:27 ` Dave Hansen
2021-08-05 14:05 ` Tianyu Lan
2021-08-05 14:05 ` Tianyu Lan
2021-08-05 14:11 ` Peter Zijlstra
2021-08-05 14:11 ` Peter Zijlstra
2021-08-05 14:23 ` Peter Zijlstra
2021-08-05 14:23 ` Peter Zijlstra
2021-08-05 14:29 ` Dave Hansen [this message]
2021-08-05 14:29 ` Dave Hansen
2021-08-05 15:51 ` Tianyu Lan
2021-08-05 15:51 ` Tianyu Lan
2021-08-04 18:45 ` [PATCH V2 04/14] x86/HV: Add new hvcall guest address host visibility support Tianyu Lan
2021-08-04 18:45 ` Tianyu Lan
2021-08-04 18:45 ` [PATCH V2 05/14] HV: Mark vmbus ring buffer visible to host in Isolation VM Tianyu Lan
2021-08-04 18:45 ` Tianyu Lan
2021-08-04 18:45 ` [PATCH V2 06/14] HV: Add Write/Read MSR registers via ghcb page Tianyu Lan
2021-08-04 18:45 ` Tianyu Lan
2021-08-04 18:45 ` [PATCH V2 07/14] HV: Add ghcb hvcall support for SNP VM Tianyu Lan
2021-08-04 18:45 ` Tianyu Lan
2021-08-04 18:45 ` [PATCH V2 08/14] HV/Vmbus: Add SNP support for VMbus channel initiate message Tianyu Lan
2021-08-04 18:45 ` Tianyu Lan
2021-08-04 18:45 ` [PATCH V2 09/14] HV/Vmbus: Initialize VMbus ring buffer for Isolation VM Tianyu Lan
2021-08-04 18:45 ` Tianyu Lan
2021-08-04 18:45 ` [PATCH V2 10/14] DMA: Add dma_map_decrypted/dma_unmap_encrypted() function Tianyu Lan
2021-08-04 18:45 ` Tianyu Lan
2021-08-05 15:56 ` Tianyu Lan
2021-08-05 15:56 ` Tianyu Lan
2021-08-04 18:45 ` [PATCH V2 11/14] x86/Swiotlb: Add Swiotlb bounce buffer remap function for HV IVM Tianyu Lan
2021-08-04 18:45 ` Tianyu Lan
2021-08-05 16:01 ` Tianyu Lan
2021-08-05 16:01 ` Tianyu Lan
2021-08-04 18:45 ` [PATCH V2 12/14] HV/IOMMU: Enable swiotlb bounce buffer for Isolation VM Tianyu Lan
2021-08-04 18:45 ` Tianyu Lan
2021-08-04 18:45 ` [PATCH V2 13/14] HV/Netvsc: Add Isolation VM support for netvsc driver Tianyu Lan
2021-08-04 18:45 ` Tianyu Lan
2021-08-04 18:45 ` [PATCH V2 14/14] HV/Storvsc: Add Isolation VM support for storvsc driver Tianyu Lan
2021-08-04 18:45 ` Tianyu Lan
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