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From: James Houghton <jthoughton@google.com>
To: Will Deacon <will@kernel.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	 Muchun Song <muchun.song@linux.dev>,
	Oscar Salvador <osalvador@suse.de>
Cc: Nikos Nikoleris <nikos.nikoleris@arm.com>,
	Linu Cherian <linu.cherian@arm.com>,
	 Mark Rutland <mark.rutland@arm.com>,
	David Hildenbrand <david@kernel.org>,
	 Andrew Morton <akpm@linux-foundation.org>,
	Ryan Roberts <ryan.roberts@arm.com>,
	 Nanyong Sun <sunnanyong@huawei.com>, Yu Zhao <yuzhao@google.com>,
	 Frank van der Linden <fvdl@google.com>,
	David Rientjes <rientjes@google.com>,
	 James Houghton <jthoughton@google.com>,
	linux-kernel@vger.kernel.org,
	 linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org
Subject: [PATCH 18/18] arm64: Remove user-selectable HVO Kconfig
Date: Wed,  8 Jul 2026 03:11:28 +0000	[thread overview]
Message-ID: <20260708031129.3503195-19-jthoughton@google.com> (raw)
In-Reply-To: <20260708031129.3503195-1-jthoughton@google.com>

The Kconfig is not ideal; it is niche and difficult to understand for
users. The Kconfig was added to avoid the following regression: if HVO
is compiled in and all boot CPUs support it, any late CPUs that do not
will not be onlined.

The implementation now avoids this regression as long as HVO is not
actively in use. Therefore, drop the Kconfig.

Signed-off-by: James Houghton <jthoughton@google.com>
---
 arch/arm64/Kconfig | 13 +------------
 1 file changed, 1 insertion(+), 12 deletions(-)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index cf4bd6bd7f11..2a59155f68dc 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -259,7 +259,7 @@ config ARM64
 	select USER_STACKTRACE_SUPPORT
 	select VDSO_GETRANDOM
 	select VMAP_STACK
-	select ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP if ARM64_WANT_OPTIMIZE_HUGETLB_VMEMMAP
+	select ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP if ARM64_HW_AFDBM
 	help
 	  ARM 64-bit (AArch64) Linux support.
 
@@ -1608,17 +1608,6 @@ config ARCH_SPARSEMEM_ENABLE
 	def_bool y
 	select SPARSEMEM_VMEMMAP_ENABLE
 
-config ARM64_WANT_OPTIMIZE_HUGETLB_VMEMMAP
-	bool "Enable support for HugeTLB Vmemmap Optimization (HVO)"
-	default n
-	depends on HUGETLB_PAGE && SPARSEMEM_VMEMMAP && ARM64_HW_AFDBM
-	help
-	  Enable support for HVO. When enabled, late-onlining of CPUs that do
-	  not support features required by HVO will not be onlined if all boot
-	  CPUs do have such support.
-
-	  If unsure, say N
-
 config HW_PERF_EVENTS
 	def_bool y
 	depends on ARM_PMU
-- 
2.55.0.795.g602f6c329a-goog



  parent reply	other threads:[~2026-07-08  3:12 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-07-08  3:11 [PATCH 00/18] Another attempt at HVO support on arm64 James Houghton
2026-07-08  3:11 ` [PATCH 01/18] hugetlb_vmemmap: Always flush TLB if needed upon PTE remapping James Houghton
2026-07-08  3:11 ` [PATCH 02/18] hugetlb_vmemmap: Move vmemmap_get_tail up James Houghton
2026-07-08  3:11 ` [PATCH 03/18] hugetlb_vmemmap: Leave pages partially HVOed upon restore failure James Houghton
2026-07-08  3:11 ` [PATCH 04/18] hugetlb_vmemmap: Use try_update_vmemmap_pte to update in-use PTEs James Houghton
2026-07-08  3:11 ` [PATCH 05/18] hugetlb_vmemmap: Allow architectures not to allow HVO at runtime James Houghton
2026-07-08  3:11 ` [PATCH 06/18] arm64: Rename cpu_has_hw_af to system_has_hw_af James Houghton
2026-07-08  3:11 ` [PATCH 07/18] arm64: Add system_supports_hvo James Houghton
2026-07-08  3:11 ` [PATCH 08/18] arm64: Implement try_update_vmemmap_pte using the AF trick James Houghton
2026-07-08  3:11 ` [PATCH 09/18] arm64: Prevent HVO if the HVO system feature is not enabled James Houghton
2026-07-08  3:11 ` [PATCH 10/18] arm64: Support hugetlb vmemmap optimization James Houghton
2026-07-08  3:11 ` [PATCH 11/18] hugetlb_vmemmap: Use try_populate_vmemmap_pmd for replacing in-use PMDs James Houghton
2026-07-08  3:11 ` [PATCH 12/18] arm64: Implement try_populate_vmemmap_pmd using AF trick James Houghton
2026-07-08  3:11 ` [PATCH 13/18] arm64: Drop BBML2_NOABORT requirement for HVO James Houghton
2026-07-08  3:11 ` [PATCH 14/18] hugetlb_vmemmap: Rename mm/hugetlb_vmemmap.h to mm/hugetlb_vmemmap_internal.h James Houghton
2026-07-08  3:11 ` [PATCH 15/18] hugetlb_vmemmap: Add a way to permanently disable HVO when needed James Houghton
2026-07-08  3:11 ` [PATCH 16/18] arm64: Allow "optional" CPU features to be required sometimes James Houghton
2026-07-08  3:11 ` [PATCH 17/18] arm64: Permit onlining of HVO-incompatible late CPUs if HVO is not in use James Houghton
2026-07-08  3:11 ` James Houghton [this message]
     [not found] ` <FC9E78F0-8FF7-44AF-A848-8401B4702488@linux.dev>
2026-07-08 16:49   ` [PATCH 00/18] Another attempt at HVO support on arm64 James Houghton
2026-07-09  9:54     ` Muchun Song
2026-07-09 19:04       ` James Houghton
2026-07-10  3:40         ` Muchun Song
2026-07-11  2:22         ` Muchun Song
2026-07-09  9:58 ` David Hildenbrand (Arm)
2026-07-10  4:58 ` Muchun Song

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