From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (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 213BC4349B4 for ; Fri, 18 Sep 2026 08:16:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789719370; cv=none; b=FKEIDYVjrPJy7VBaq0RgLDEI8cUQTebLjRorO2T5EcXsdD8+sgT/FzPBQHc8nU2l0bF3WOxJfFz6STkoubNG3/ba7tTk5vaZg+gRtTRCQ18RTAZqJ+Swgbe1lE0oZWaOL10VeBbWeU4g/w/sVaw6KEE1u7TcKyqOE6mT37KtM2I= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789719370; c=relaxed/simple; bh=3W9xldtaGe7Ff2NkNCQJOcGzl15r04ouTawyPDxtIbs=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=CaQgMaEAb5lYZJYQs4Mo4yxi1mNvzRVqAqrIn5Cg3jrXQclQLmcdtF6Yszh5FOc/YOlSOqUQ3bFHivAIpeziOYQZJuN0u3iEVYliKsR4izZIrOsLnh/5O6MmgxRpxOoTOMMJEOvSesLS3jSdgsvi36vo172LtGz5n5GnqVJ30j0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=ht4K3JGO; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="ht4K3JGO" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1789719363; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=qTS8CM36DMSHYjVobhMBvWQts9TN4lc2TtJAx1vS/HI=; b=ht4K3JGOJ2BIDPD+qWWVTHmgi+hnRj6oE5HP0trZTX8Bktdaxx8LxhHbpmqmjaWr9KxCVJ pD4fYFUYDvVosQTxFoQ/wCI05GDRcUDC9eRH/zmusXgcx19AlELZhrvaCuUPSpvmT/GPVt k5y9KXQxTTCdgWbd5h82gCMBEnlQkpc= Received: from mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-37-nM4JldxnPD6IlP0LxSbQbw-1; Fri, 18 Sep 2026 04:16:00 -0400 X-MC-Unique: nM4JldxnPD6IlP0LxSbQbw-1 X-Mimecast-MFC-AGG-ID: nM4JldxnPD6IlP0LxSbQbw_1789719359 Received: from mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.4]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 48E89195604E; Fri, 18 Sep 2026 08:15:59 +0000 (UTC) Received: from virtlab1023.virt.eng.rdu2.dc.redhat.com (virtlab1023.virt.eng.rdu2.dc.redhat.com [10.18.48.26]) by mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 9DE5E30001A2; Fri, 18 Sep 2026 08:15:58 +0000 (UTC) From: Paolo Bonzini To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: nsaenz@amazon.com, vkuznets@redhat.com, snambakam@linux.microsoft.com Subject: [PATCH v2 17/28] KVM: Introduce kvm_check_gen()/kvm_memslots_check_gen() Date: Fri, 18 Sep 2026 04:15:32 -0400 Message-ID: <20260918081543.139871-18-pbonzini@redhat.com> In-Reply-To: <20260918081543.139871-1-pbonzini@redhat.com> References: <20260918081543.139871-1-pbonzini@redhat.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.4 In many cases, retrieving kvm_memslots is followed by a check on the generation of the slots. Introduce a helper function that either does the check alone, or compounds it with returning the struct kvm_memslots* to the caller. Signed-off-by: Paolo Bonzini --- arch/x86/kvm/x86.c | 10 ++-------- include/linux/kvm_host.h | 13 +++++++++++++ virt/kvm/kvm_main.c | 8 ++++---- virt/kvm/pfncache.c | 10 ++++------ 4 files changed, 23 insertions(+), 18 deletions(-) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 6c0c95b92b5a..5b7ff5d9af75 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -2049,7 +2049,6 @@ static void record_steal_time(struct kvm_vcpu *vcpu) { struct gfn_to_hva_cache *ghc = &vcpu->arch.st.cache; struct kvm_steal_time __user *st; - struct kvm_memslots *slots; gpa_t gpa = vcpu->arch.st.msr_val & KVM_STEAL_VALID_BITS; u64 steal; u32 version; @@ -2065,9 +2064,7 @@ static void record_steal_time(struct kvm_vcpu *vcpu) if (WARN_ON_ONCE(current->mm != vcpu->kvm->mm)) return; - slots = kvm_memslots(vcpu->kvm); - - if (unlikely(slots->generation != ghc->generation || + if (unlikely(!kvm_check_gen(vcpu->kvm, ghc->generation) || gpa != ghc->gpa || kvm_is_error_hva(ghc->hva) || !ghc->memslot)) { /* We rely on the fact that it fits in a single page. */ @@ -2617,7 +2614,6 @@ static void kvm_steal_time_set_preempted(struct kvm_vcpu *vcpu) { struct gfn_to_hva_cache *ghc = &vcpu->arch.st.cache; struct kvm_steal_time __user *st; - struct kvm_memslots *slots; static const u8 preempted = KVM_VCPU_PREEMPTED; gpa_t gpa = vcpu->arch.st.msr_val & KVM_STEAL_VALID_BITS; @@ -2644,9 +2640,7 @@ static void kvm_steal_time_set_preempted(struct kvm_vcpu *vcpu) if (unlikely(current->mm != vcpu->kvm->mm)) return; - slots = kvm_memslots(vcpu->kvm); - - if (unlikely(slots->generation != ghc->generation || + if (unlikely(!kvm_check_gen(vcpu->kvm, ghc->generation) || gpa != ghc->gpa || kvm_is_error_hva(ghc->hva) || !ghc->memslot)) return; diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 24d04322d89e..7599ab7ad7ef 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -2644,6 +2644,19 @@ static inline int kvm_mem_attributes_may_write_gfn(struct kvm *kvm, gfn_t gfn) return kvm_mem_attributes_may_write(attrs); } +static inline bool kvm_memslots_check_gen(struct kvm *kvm, u64 slots_generation, struct kvm_memslots **p_slots) +{ + struct kvm_memslots *slots = *p_slots = kvm_memslots(kvm); + return slots->generation == slots_generation; +} + +static inline bool kvm_check_gen(struct kvm *kvm, u64 slots_generation) +{ + struct kvm_memslots *slots; + return kvm_memslots_check_gen(kvm, slots_generation, &slots); +} + + #ifdef CONFIG_KVM_GUEST_MEMFD int kvm_gmem_get_pfn(struct kvm *kvm, struct kvm_memory_slot *slot, gfn_t gfn, kvm_pfn_t *pfn, struct page **page, diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 994a33a09448..89e79d3f27f0 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -3523,14 +3523,14 @@ int kvm_write_guest_offset_cached(struct kvm *kvm, struct gfn_to_hva_cache *ghc, void *data, unsigned int offset, unsigned long len) { - struct kvm_memslots *slots = kvm_memslots(kvm); + struct kvm_memslots *slots; int r; gpa_t gpa = ghc->gpa + offset; if (WARN_ON_ONCE(len + offset > ghc->len)) return -EINVAL; - if (slots->generation != ghc->generation) { + if (unlikely(!kvm_memslots_check_gen(kvm, ghc->generation, &slots))) { if (__kvm_gfn_to_hva_cache_init(slots, ghc, ghc->gpa, ghc->len)) return -EFAULT; } @@ -3561,14 +3561,14 @@ int kvm_read_guest_offset_cached(struct kvm *kvm, struct gfn_to_hva_cache *ghc, void *data, unsigned int offset, unsigned long len) { - struct kvm_memslots *slots = kvm_memslots(kvm); + struct kvm_memslots *slots; int r; gpa_t gpa = ghc->gpa + offset; if (WARN_ON_ONCE(len + offset > ghc->len)) return -EINVAL; - if (slots->generation != ghc->generation) { + if (unlikely(!kvm_memslots_check_gen(kvm, ghc->generation, &slots))) { if (__kvm_gfn_to_hva_cache_init(slots, ghc, ghc->gpa, ghc->len)) return -EFAULT; } diff --git a/virt/kvm/pfncache.c b/virt/kvm/pfncache.c index 728d2c1b488a..e09703d249bb 100644 --- a/virt/kvm/pfncache.c +++ b/virt/kvm/pfncache.c @@ -72,8 +72,6 @@ static bool kvm_gpc_is_valid_len(gpa_t gpa, unsigned long uhva, bool kvm_gpc_check(struct gfn_to_pfn_cache *gpc, unsigned long len) { - struct kvm_memslots *slots = kvm_memslots(gpc->kvm); - if (!gpc->active) return false; @@ -81,7 +79,7 @@ bool kvm_gpc_check(struct gfn_to_pfn_cache *gpc, unsigned long len) * If the page was cached from a memslot, make sure the memslots have * not been re-configured. */ - if (!kvm_is_error_gpa(gpc->gpa) && gpc->generation != slots->generation) + if (!kvm_is_error_gpa(gpc->gpa) && !kvm_check_gen(gpc->kvm, gpc->generation)) return false; if (kvm_is_error_hva(gpc->uhva)) @@ -290,12 +288,12 @@ static int __kvm_gpc_refresh(struct gfn_to_pfn_cache *gpc, gpa_t gpa, unsigned l if (gpc->uhva != old_uhva) hva_change = true; } else { - struct kvm_memslots *slots = kvm_memslots(gpc->kvm); + struct kvm_memslots *slots; page_offset = offset_in_page(gpa); - if (gpc->gpa != gpa || gpc->generation != slots->generation || - kvm_is_error_hva(gpc->uhva)) { + if (!kvm_memslots_check_gen(gpc->kvm, gpc->generation, &slots) || + gpc->gpa != gpa || kvm_is_error_hva(gpc->uhva)) { gfn_t gfn = gpa_to_gfn(gpa); gpc->gpa = gpa; -- 2.52.0