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AHgh+RoMprP1ZEyxyWaBpz4z44VxX5D3NmceXXLaq3j4DJ9BkRqwE6ei3cHmcnjUwrcJzU/No+bIWm8Wag==@kvack.org X-Gm-Message-State: AOJu0YzBgW+gUyY7i7GpnFPh/5SZ6AIZxZk8jKR8DxxHQywp6WprAMtz ocWCl16PP86Rm777WdWkcj8AO2hjxF5QbhiBAQvXDfdvY6YJwxYPjua5zRzYZ2sMAyQYB4j/Nla V0w9FufrqvMeRVHxT01dQAQ== X-Received: from plbkq14.prod.google.com ([2002:a17:903:284e:b0:2c7:e8ed:e941]) (user=jthoughton job=prod-delivery.src-stubby-dispatcher) by 2002:a17:903:1b4e:b0:2ca:d658:d874 with SMTP id d9443c01a7336-2ccea45e8camr7594005ad.23.1783480299668; Tue, 07 Jul 2026 20:11:39 -0700 (PDT) Date: Wed, 8 Jul 2026 03:11:17 +0000 In-Reply-To: <20260708031129.3503195-1-jthoughton@google.com> Mime-Version: 1.0 References: <20260708031129.3503195-1-jthoughton@google.com> X-Mailer: git-send-email 2.55.0.795.g602f6c329a-goog Message-ID: <20260708031129.3503195-8-jthoughton@google.com> Subject: [PATCH 07/18] arm64: Add system_supports_hvo From: James Houghton To: Will Deacon , Catalin Marinas , Muchun Song , Oscar Salvador Cc: Nikos Nikoleris , Linu Cherian , Mark Rutland , David Hildenbrand , Andrew Morton , Ryan Roberts , Nanyong Sun , Yu Zhao , Frank van der Linden , David Rientjes , James Houghton , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org Content-Type: text/plain; charset="UTF-8" X-Rspamd-Queue-Id: 1B3C0A0005 X-Stat-Signature: x7yp8b8z18topcgx8ujqrbqybj6jmik1 X-Rspam-User: X-Rspamd-Server: rspam12 X-HE-Tag: 1783480300-368865 X-HE-Meta: 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 MX3kZD4u 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Track HVO compatibility as its own system feature. If every boot CPU supports it, later onlining a CPU that doesn't support it won't be allowed. HVO requires BBM Level 2 no abort for the block -> table transitions when optimizing the vmemmap, and it requires hardware AF management to avoid taking page faults on the !AF translation that is installed as part of the RW table -> RO + new OA table transitions. Another possibility would be to disable HVO if an incompatible CPU were onlined; I haven't done this. Signed-off-by: James Houghton --- arch/arm64/include/asm/cpucaps.h | 2 ++ arch/arm64/include/asm/cpufeature.h | 5 +++++ arch/arm64/kernel/cpufeature.c | 16 ++++++++++++++++ arch/arm64/tools/cpucaps | 1 + 4 files changed, 24 insertions(+) diff --git a/arch/arm64/include/asm/cpucaps.h b/arch/arm64/include/asm/cpucaps.h index 25c61cda901c..6db3ef827f86 100644 --- a/arch/arm64/include/asm/cpucaps.h +++ b/arch/arm64/include/asm/cpucaps.h @@ -75,6 +75,8 @@ cpucap_is_possible(const unsigned int cap) return IS_ENABLED(CONFIG_HW_PERF_EVENTS); case ARM64_HAS_LSUI: return IS_ENABLED(CONFIG_ARM64_LSUI); + case ARM64_HVO_COMPATIBLE: + return IS_ENABLED(CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP); } return true; diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h index e818ad1b56e2..a62c284962cf 100644 --- a/arch/arm64/include/asm/cpufeature.h +++ b/arch/arm64/include/asm/cpufeature.h @@ -885,6 +885,11 @@ static inline bool system_supports_bbml2_noabort(void) return alternative_has_cap_unlikely(ARM64_HAS_BBML2_NOABORT); } +static inline bool system_supports_hvo(void) +{ + return alternative_has_cap_unlikely(ARM64_HVO_COMPATIBLE); +} + int do_emulate_mrs(struct pt_regs *regs, u32 sys_reg, u32 rt); bool try_emulate_mrs(struct pt_regs *regs, u32 isn); diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index 9a22df0c5120..3b9224b99a5f 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -2172,6 +2172,16 @@ static bool has_bbml2_noabort(const struct arm64_cpu_capabilities *caps, int sco return cpu_supports_bbml2_noabort(); } +static bool hvo_compatible(const struct arm64_cpu_capabilities *caps, int scope) +{ + /* + * We need BBML2 to support Block -> Table transitions without taking + * faults, and we need HW AF support to support changing the OA without + * taking faults. + */ + return cpu_supports_bbml2_noabort() && supports_hw_af(scope); +} + static void cpu_enable_pan(const struct arm64_cpu_capabilities *__unused) { /* @@ -3067,6 +3077,12 @@ static const struct arm64_cpu_capabilities arm64_features[] = { .type = ARM64_CPUCAP_EARLY_LOCAL_CPU_FEATURE, .matches = has_bbml2_noabort, }, + { + .desc = "HugeTLB Vmemmap Optimization Support", + .capability = ARM64_HVO_COMPATIBLE, + .type = ARM64_CPUCAP_SYSTEM_FEATURE, + .matches = hvo_compatible, + }, { .desc = "52-bit Virtual Addressing for KVM (LPA2)", .capability = ARM64_HAS_LPA2, diff --git a/arch/arm64/tools/cpucaps b/arch/arm64/tools/cpucaps index 9b85a84f6fd4..630953d59c52 100644 --- a/arch/arm64/tools/cpucaps +++ b/arch/arm64/tools/cpucaps @@ -70,6 +70,7 @@ HAS_VIRT_HOST_EXTN HAS_WFXT HAS_XNX HAFT +HVO_COMPATIBLE HW_DBM KVM_HVHE KVM_PROTECTED_MODE -- 2.55.0.795.g602f6c329a-goog