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Wed, 24 Sep 2025 17:11:31 +0200 (CEST) From: Patrick Roy To: Cc: Patrick Roy , pbonzini@redhat.com, corbet@lwn.net, maz@kernel.org, oliver.upton@linux.dev, joey.gouly@arm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com, catalin.marinas@arm.com, will@kernel.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, luto@kernel.org, peterz@infradead.org, willy@infradead.org, akpm@linux-foundation.org, david@redhat.com, lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, vbabka@suse.cz, rppt@kernel.org, surenb@google.com, mhocko@suse.com, song@kernel.org, jolsa@kernel.org, ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, martin.lau@linux.dev, eddyz87@gmail.com, yonghong.song@linux.dev, john.fastabend@gmail.com, kpsingh@kernel.org, sdf@fomichev.me, haoluo@google.com, jgg@ziepe.ca, jhubbard@nvidia.com, peterx@redhat.com, jannh@google.com, pfalcato@suse.de, shuah@kernel.org, seanjc@google.com, kvm@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, bpf@vger.kernel.org, linux-kselftest@vger.kernel.org, xmarcalx@amazon.co.uk, kalyazin@amazon.co.uk, jackabt@amazon.co.uk, derekmn@amazon.co.uk, tabba@google.com, ackerleytng@google.com Subject: [PATCH v7 02/12] x86/tlb: export flush_tlb_kernel_range to KVM module Date: Wed, 24 Sep 2025 16:10:42 +0100 Message-ID: <20250924151101.2225820-3-patrick.roy@campus.lmu.de> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20250924151101.2225820-1-patrick.roy@campus.lmu.de> References: <20250924151101.2225820-1-patrick.roy@campus.lmu.de> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Patrick Roy After direct map removal, a TLB flush can be done to ensure that the just-unmapped memory cannot be accessed through stale TLB entries. This is particularly useful on modern hardware, where one can not rely on timely TLB-eviction to ensure these entries go away. This export is only needed on x86, as arm64 (the only other architecture supporting guest_memfd currently) does not allow building KVM as a module. Cc: Thomas Gleixner Signed-off-by: Patrick Roy --- arch/x86/include/asm/tlbflush.h | 3 ++- arch/x86/mm/tlb.c | 1 + 2 files changed, 3 insertions(+), 1 deletion(-) diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflus= h.h index 00daedfefc1b..6f57f7eb621b 100644 --- a/arch/x86/include/asm/tlbflush.h +++ b/arch/x86/include/asm/tlbflush.h @@ -317,7 +317,6 @@ extern void flush_tlb_all(void); extern void flush_tlb_mm_range(struct mm_struct *mm, unsigned long start, unsigned long end, unsigned int stride_shift, bool freed_tables); -extern void flush_tlb_kernel_range(unsigned long start, unsigned long end); =20 static inline void flush_tlb_page(struct vm_area_struct *vma, unsigned lon= g a) { @@ -483,6 +482,8 @@ static inline void cpu_tlbstate_update_lam(unsigned lon= g lam, u64 untag_mask) #endif #endif /* !MODULE */ =20 +extern void flush_tlb_kernel_range(unsigned long start, unsigned long end); + static inline void __native_tlb_flush_global(unsigned long cr4) { native_write_cr4(cr4 ^ X86_CR4_PGE); diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c index 39f80111e6f1..dee5018bceeb 100644 --- a/arch/x86/mm/tlb.c +++ b/arch/x86/mm/tlb.c @@ -1541,6 +1541,7 @@ void flush_tlb_kernel_range(unsigned long start, unsi= gned long end) =20 put_flush_tlb_info(); } +EXPORT_SYMBOL_FOR_MODULES(flush_tlb_kernel_range, "kvm"); =20 /* * This can be used from process context to figure out what the value of --=20 2.51.0