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Received: from fangorn.home.surriel.com ([10.0.13.7]) by shelob.surriel.com with esmtpsa (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.97.1) (envelope-from ) id 1vMWI9-000000003i4-1keH; Fri, 21 Nov 2025 13:55:34 -0500 From: Rik van Riel To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, x86@kernel.org, dave.hansen@linux.intel.com, peterz@infradead.org, kernel-team@meta.com, bp@alien8.de, Rik van Riel , Rik van Riel Subject: [RFC v5 6/8] x86/mm: use RAR for kernel TLB flushes Date: Fri, 21 Nov 2025 13:54:27 -0500 Message-ID: <20251121185530.21876-7-riel@surriel.com> X-Mailer: git-send-email 2.51.1 In-Reply-To: <20251121185530.21876-1-riel@surriel.com> References: <20251121185530.21876-1-riel@surriel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Stat-Signature: 7dw6qh7p4xq5dzneary9ydhzqgkspkjd X-Rspam-User: X-Rspamd-Queue-Id: 548F710000B X-Rspamd-Server: rspam10 X-HE-Tag: 1763751343-819583 X-HE-Meta: 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 hhXEiS3m YU1XqK//T2f4gWj4aGu7dz86Hv1QXj0x09bOiNOcrtDdqZiYhQY2oE9UwJaCjp2IN8ZY3ttu5wBiqVmjcp1L3Dz5A4UVpMhHk2Cyf1yNlONBtCWkIiJZzHZTcCR/KU0zAtZyjZ8LgYxjAn6M4Co8RMiRFC47RM9i/jK6X+q9fdJ4MOnxHVQ0+pMEsG9JSUudw4+J9gWS9XP0aKObZRj49O6C3qljKx+ClKEAT03IDcemvzAoevV22Ya2IZTga+/bzOHXMZwzVkMkeNNSkhwHWJVKsK7EGKBiYo7S/ X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: From: Rik van Riel Use Intel RAR for kernel TLB flushes, when enabled. Pass in PCID 0 to smp_call_rar_many() to flush the specified addresses, regardless of which PCID they might be cached under in any destination CPU. Signed-off-by: Rik van Riel --- arch/x86/mm/tlb.c | 36 ++++++++++++++++++++++++++++++++++++ 1 file changed, 36 insertions(+) diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c index f5b93e01e347..19c28386d8de 100644 --- a/arch/x86/mm/tlb.c +++ b/arch/x86/mm/tlb.c @@ -22,6 +22,7 @@ #include #include #include +#include #include #include "mm_internal.h" @@ -1489,6 +1490,17 @@ static void do_flush_tlb_all(void *info) __flush_tlb_all(); } +static void rar_full_flush(const cpumask_t *cpumask) +{ + guard(preempt)(); + smp_call_rar_many(cpumask, 0, 0, TLB_FLUSH_ALL); +} + +static void rar_flush_all(void) +{ + rar_full_flush(cpu_online_mask); +} + void flush_tlb_all(void) { count_vm_tlb_event(NR_TLB_REMOTE_FLUSH); @@ -1496,6 +1508,8 @@ void flush_tlb_all(void) /* First try (faster) hardware-assisted TLB invalidation. */ if (cpu_feature_enabled(X86_FEATURE_INVLPGB)) invlpgb_flush_all(); + else if (cpu_feature_enabled(X86_FEATURE_RAR)) + rar_flush_all(); else /* Fall back to the IPI-based invalidation. */ on_each_cpu(do_flush_tlb_all, NULL, 1); @@ -1525,15 +1539,35 @@ static void do_kernel_range_flush(void *info) struct flush_tlb_info *f = info; unsigned long addr; + /* + * With PTI kernel TLB entries in all PCIDs need to be flushed. + * With RAR the PCID space becomes so large, we might as well flush it all. + * + * Either of the two by itself works with targeted flushes. + */ + if (cpu_feature_enabled(X86_FEATURE_RAR) && + cpu_feature_enabled(X86_FEATURE_PTI)) { + invpcid_flush_all(); + return; + } + /* flush range by one by one 'invlpg' */ for (addr = f->start; addr < f->end; addr += PAGE_SIZE) flush_tlb_one_kernel(addr); } +static void rar_kernel_range_flush(struct flush_tlb_info *info) +{ + guard(preempt)(); + smp_call_rar_many(cpu_online_mask, 0, info->start, info->end); +} + static void kernel_tlb_flush_all(struct flush_tlb_info *info) { if (cpu_feature_enabled(X86_FEATURE_INVLPGB)) invlpgb_flush_all(); + else if (cpu_feature_enabled(X86_FEATURE_RAR)) + rar_flush_all(); else on_each_cpu(do_flush_tlb_all, NULL, 1); } @@ -1542,6 +1576,8 @@ static void kernel_tlb_flush_range(struct flush_tlb_info *info) { if (cpu_feature_enabled(X86_FEATURE_INVLPGB)) invlpgb_kernel_range_flush(info); + else if (cpu_feature_enabled(X86_FEATURE_RAR)) + rar_kernel_range_flush(info); else on_each_cpu(do_kernel_range_flush, info, 1); } -- 2.51.1