From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9C35B27EC7C; Tue, 16 Jun 2026 00:42:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781570545; cv=none; b=qhBtj3L1Eq9AL5N6SmQ4s036lfgL5d/xmlh7gaIAcHQzkdD+NcFXHJI6M7y54dcHtfx5Bl6EKdOnwLaTOUffkV+d93GXMsj8zPDmXAMSshqeP6Ad5WFclRwK2bSQ5N6FFGDsYzJfffyBS9g/O0RI5lb/kRl3zlVIdwkS5JXkSAI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781570545; c=relaxed/simple; bh=LpE2D8JeuiHftJQvIS9kagZYnYqpxAOcqHCzNhSf1xg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=szqfuZWQLuQ2tUcR5YOyEyxrvta6W0bg+QMHwSnk/cGteIpEYwAnO8bBPLDCeScdBBg9mvCnEcCPcCG3lkBhgd7fYJGjGA7kXLo0eU7/URMmn9GOB0olK2Lybby7GMmwz/ZVm7CPQlGigFiJo7RZoP2jyLJaDwzJuYYjHKGaxzI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=n1ROir2b; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="n1ROir2b" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 306431F00A3A; Tue, 16 Jun 2026 00:42:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1781570543; bh=lws1dRSnHsKo/9vA/82BsxaXe+bSynL/lwearvOELG0=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=n1ROir2bAvW4ojediJZrP/O/ODPS69XqZ9LxldWy+CPZqAK5yudDxv54wktJDmo88 iu8kDRK9HvlKex6E+juIjUvvuEmtBNfvBRdSAgSO7ZwaNQwBkJAWLZ0CjS1rX29xhb zCn0zZxls22XLIRxaW+txefdiW0w5ZKc416aSg3ML/SS14ZkiYbgbpbYXQKPuROIf0 vhkERcJKrOl0CI03M/nctHcf9rkn1R/dUEyrNWJsIsbPrZf4t7Y0vv1UO/Jt/N8+6O Ib2pRLfQHCFTN3clkHBdkrA0Y17ww+kf+359z9S2xVPi6zdksZndWts+FvUuv/cq7H 38bu9I/otwTWg== From: Yosry Ahmed To: Sean Christopherson Cc: Paolo Bonzini , Jim Mattson , Maxim Levitsky , Vitaly Kuznetsov , Tom Lendacky , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Yosry Ahmed Subject: [RFC PATCH v2 04/25] KVM: x86/mmu: Support specifying a minimum TLB tag Date: Tue, 16 Jun 2026 00:41:33 +0000 Message-ID: <20260616004155.1435766-5-yosry@kernel.org> X-Mailer: git-send-email 2.54.0.1136.gdb2ca164c4-goog In-Reply-To: <20260616004155.1435766-1-yosry@kernel.org> References: <20260616004155.1435766-1-yosry@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit In preparation for using the TLB tags allocator for SVM, which has a range of ASIDs allocated for SEV/SNP, pass in a minimum TLB tag when initializing the TLB tags allocator. The bitmap is conceptually shifted such that bit=0 corresponds to tag=min. Specifying the minimum value during initialization also makes the API clearer, as the passed number of tags becomes the actual number of *usable* tags, and tag=0 is explicitly excluded by the caller. No functional change intended for VMX as VPID=0 is not used anyway. Signed-off-by: Yosry Ahmed --- arch/x86/kvm/mmu.h | 2 +- arch/x86/kvm/mmu/mmu.c | 38 +++++++++++++++++++++++--------------- arch/x86/kvm/vmx/vmx.h | 3 ++- 3 files changed, 26 insertions(+), 17 deletions(-) diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h index 9a2916012cbff..cfffee92b8b71 100644 --- a/arch/x86/kvm/mmu.h +++ b/arch/x86/kvm/mmu.h @@ -337,7 +337,7 @@ static inline bool kvm_is_gfn_alias(struct kvm *kvm, gfn_t gfn) typedef unsigned int kvm_tlb_tag_t; -int kvm_init_tlb_tags(unsigned int nr); +int kvm_init_tlb_tags(kvm_tlb_tag_t min, unsigned int nr); void kvm_destroy_tlb_tags(void); kvm_tlb_tag_t kvm_alloc_tlb_tag(void); void kvm_free_tlb_tag(kvm_tlb_tag_t tag); diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index e021ed562502f..bf2e0c2205631 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -8197,24 +8197,26 @@ static struct { spinlock_t lock; unsigned long *bitmap; unsigned int nr; + kvm_tlb_tag_t min; } tlb_tags; -int kvm_init_tlb_tags(unsigned int nr) +int kvm_init_tlb_tags(kvm_tlb_tag_t min, unsigned int nr) { - if (WARN_ON_ONCE(!nr)) - return -EINVAL; - - tlb_tags.bitmap = bitmap_zalloc(nr, GFP_KERNEL); - if (!tlb_tags.bitmap) - return -ENOMEM; + unsigned int end; /* * 0 is the host's TLB tag for both VMX's VPID and SVM's ASID, and is * returned on failed allocations (e.g. no more tags left). */ - __set_bit(0, tlb_tags.bitmap); + if (WARN_ON_ONCE(!min || !nr || check_add_overflow(min, nr, &end))) + return -EINVAL; + + tlb_tags.bitmap = bitmap_zalloc(nr, GFP_KERNEL); + if (!tlb_tags.bitmap) + return -ENOMEM; tlb_tags.nr = nr; + tlb_tags.min = min; spin_lock_init(&tlb_tags.lock); return 0; } @@ -8229,30 +8231,36 @@ EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_destroy_tlb_tags); kvm_tlb_tag_t kvm_alloc_tlb_tag(void) { - kvm_tlb_tag_t tag; + unsigned int bit; if (WARN_ON_ONCE(!tlb_tags.bitmap)) return 0; guard(spinlock)(&tlb_tags.lock); - tag = find_first_zero_bit(tlb_tags.bitmap, tlb_tags.nr); - if (tag >= tlb_tags.nr) + bit = find_first_zero_bit(tlb_tags.bitmap, tlb_tags.nr); + if (bit >= tlb_tags.nr) return 0; - __set_bit(tag, tlb_tags.bitmap); - return tag; + __set_bit(bit, tlb_tags.bitmap); + return tlb_tags.min + bit; } EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_alloc_tlb_tag); void kvm_free_tlb_tag(kvm_tlb_tag_t tag) { - if (!tag || WARN_ON_ONCE(tag >= tlb_tags.nr)) + unsigned int bit; + + if (!tag || WARN_ON_ONCE(tag < tlb_tags.min)) + return; + + bit = tag - tlb_tags.min; + if (WARN_ON_ONCE(bit >= tlb_tags.nr)) return; guard(spinlock)(&tlb_tags.lock); - __clear_bit(tag, tlb_tags.bitmap); + __clear_bit(bit, tlb_tags.bitmap); } EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_free_tlb_tag); diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h index d6d35637d94f8..0ddfe9626c126 100644 --- a/arch/x86/kvm/vmx/vmx.h +++ b/arch/x86/kvm/vmx/vmx.h @@ -336,7 +336,8 @@ static __always_inline u32 vmx_get_intr_info(struct kvm_vcpu *vcpu) static __always_inline int init_vpids(void) { - return enable_vpid ? kvm_init_tlb_tags(VMX_NR_VPIDS) : 0; + /* Exclude VPID=0 as it is used for the host */ + return enable_vpid ? kvm_init_tlb_tags(1, VMX_NR_VPIDS - 1) : 0; } static __always_inline void destroy_vpids(void) -- 2.54.0.1136.gdb2ca164c4-goog