From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mm01.cs.columbia.edu (mm01.cs.columbia.edu [128.59.11.253]) by smtp.lore.kernel.org (Postfix) with ESMTP id 369E2FA3740 for ; Thu, 27 Oct 2022 22:19:42 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id D6BFC49EC4; Thu, 27 Oct 2022 18:19:41 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu Authentication-Results: mm01.cs.columbia.edu (amavisd-new); dkim=softfail (fail, message has been altered) header.i=@linux.dev Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 96Y8n3deCZeU; Thu, 27 Oct 2022 18:19:40 -0400 (EDT) Received: from mm01.cs.columbia.edu (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id AF04040431; Thu, 27 Oct 2022 18:19:40 -0400 (EDT) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id D8C0E40D02 for ; Thu, 27 Oct 2022 18:19:38 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id KQg9DgoB+J6p for ; Thu, 27 Oct 2022 18:19:37 -0400 (EDT) Received: from out2.migadu.com (out2.migadu.com [188.165.223.204]) by mm01.cs.columbia.edu (Postfix) with ESMTPS id AB9C449EC4 for ; Thu, 27 Oct 2022 18:19:37 -0400 (EDT) X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1666909177; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Mv1EXk7b0WRNpMnuTJ2F6nnFei9j0WoAuUnFOLgvpnk=; b=xQcvENmIKTrwxjDK/dw9mPYRkebIm2+wuy76Rpz17/OUnBpoD2GBhkWpMqv6Ekr2045RFt 5pEOMLRMNZHPMDx09Izme5XI8ZPR4DhbvwDzB1a9a+Uqv6CCXIKZi99mQxxMv5SzSWu0Hr kQ8t4baYvOL0/zfhsXR65miYBlRXJUA= From: Oliver Upton To: Marc Zyngier , James Morse , Alexandru Elisei Subject: [PATCH v3 09/15] KVM: arm64: Free removed stage-2 tables in RCU callback Date: Thu, 27 Oct 2022 22:17:46 +0000 Message-Id: <20221027221752.1683510-10-oliver.upton@linux.dev> In-Reply-To: <20221027221752.1683510-1-oliver.upton@linux.dev> References: <20221027221752.1683510-1-oliver.upton@linux.dev> MIME-Version: 1.0 X-Migadu-Flow: FLOW_OUT Cc: kvm@vger.kernel.org, kvmarm@lists.linux.dev, Ben Gardon , David Matlack , Will Deacon , kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org X-BeenThere: kvmarm@lists.cs.columbia.edu X-Mailman-Version: 2.1.14 Precedence: list List-Id: Where KVM/ARM decisions are made List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu There is no real urgency to free a stage-2 subtree that was pruned. Nonetheless, KVM does the tear down in the stage-2 fault path while holding the MMU lock. Free removed stage-2 subtrees after an RCU grace period. To guarantee all stage-2 table pages are freed before killing a VM, add an rcu_barrier() to the flush path. Signed-off-by: Oliver Upton --- arch/arm64/include/asm/kvm_pgtable.h | 2 +- arch/arm64/kvm/mmu.c | 14 +++++++++++++- 2 files changed, 14 insertions(+), 2 deletions(-) diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h index d1859e8550df..f35e7d4d73f1 100644 --- a/arch/arm64/include/asm/kvm_pgtable.h +++ b/arch/arm64/include/asm/kvm_pgtable.h @@ -65,7 +65,7 @@ typedef kvm_pte_t __rcu *kvm_pteref_t; static inline kvm_pte_t *kvm_dereference_pteref(kvm_pteref_t pteref, bool shared) { - return rcu_dereference_check(pteref, shared); + return rcu_dereference_check(pteref, !shared); } static inline void kvm_pgtable_walk_begin(void) diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c index 175a0e9a04b6..a1a623c5b069 100644 --- a/arch/arm64/kvm/mmu.c +++ b/arch/arm64/kvm/mmu.c @@ -130,9 +130,21 @@ static void kvm_s2_free_pages_exact(void *virt, size_t size) static struct kvm_pgtable_mm_ops kvm_s2_mm_ops; +static void stage2_free_removed_table_rcu_cb(struct rcu_head *head) +{ + struct page *page = container_of(head, struct page, rcu_head); + void *pgtable = page_to_virt(page); + u32 level = page_private(page); + + kvm_pgtable_stage2_free_removed(&kvm_s2_mm_ops, pgtable, level); +} + static void stage2_free_removed_table(void *addr, u32 level) { - kvm_pgtable_stage2_free_removed(&kvm_s2_mm_ops, addr, level); + struct page *page = virt_to_page(addr); + + set_page_private(page, (unsigned long)level); + call_rcu(&page->rcu_head, stage2_free_removed_table_rcu_cb); } static void kvm_host_get_page(void *addr) -- 2.38.1.273.g43a17bfeac-goog _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out2.migadu.com (out2.migadu.com [188.165.223.204]) (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 6AFA37B for ; Thu, 27 Oct 2022 22:19:38 +0000 (UTC) X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1666909177; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Mv1EXk7b0WRNpMnuTJ2F6nnFei9j0WoAuUnFOLgvpnk=; b=xQcvENmIKTrwxjDK/dw9mPYRkebIm2+wuy76Rpz17/OUnBpoD2GBhkWpMqv6Ekr2045RFt 5pEOMLRMNZHPMDx09Izme5XI8ZPR4DhbvwDzB1a9a+Uqv6CCXIKZi99mQxxMv5SzSWu0Hr kQ8t4baYvOL0/zfhsXR65miYBlRXJUA= From: Oliver Upton To: Marc Zyngier , James Morse , Alexandru Elisei Cc: linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, Reiji Watanabe , Ricardo Koller , David Matlack , Quentin Perret , Ben Gardon , Gavin Shan , Peter Xu , Will Deacon , Sean Christopherson , kvmarm@lists.linux.dev, Oliver Upton Subject: [PATCH v3 09/15] KVM: arm64: Free removed stage-2 tables in RCU callback Date: Thu, 27 Oct 2022 22:17:46 +0000 Message-ID: <20221027221752.1683510-10-oliver.upton@linux.dev> In-Reply-To: <20221027221752.1683510-1-oliver.upton@linux.dev> References: <20221027221752.1683510-1-oliver.upton@linux.dev> Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT Message-ID: <20221027221746.3vZ2Jf3tRPrMiR_iHuDwh6w7nBNz1GZP0cf5NZyFrnQ@z> There is no real urgency to free a stage-2 subtree that was pruned. Nonetheless, KVM does the tear down in the stage-2 fault path while holding the MMU lock. Free removed stage-2 subtrees after an RCU grace period. To guarantee all stage-2 table pages are freed before killing a VM, add an rcu_barrier() to the flush path. Signed-off-by: Oliver Upton --- arch/arm64/include/asm/kvm_pgtable.h | 2 +- arch/arm64/kvm/mmu.c | 14 +++++++++++++- 2 files changed, 14 insertions(+), 2 deletions(-) diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h index d1859e8550df..f35e7d4d73f1 100644 --- a/arch/arm64/include/asm/kvm_pgtable.h +++ b/arch/arm64/include/asm/kvm_pgtable.h @@ -65,7 +65,7 @@ typedef kvm_pte_t __rcu *kvm_pteref_t; static inline kvm_pte_t *kvm_dereference_pteref(kvm_pteref_t pteref, bool shared) { - return rcu_dereference_check(pteref, shared); + return rcu_dereference_check(pteref, !shared); } static inline void kvm_pgtable_walk_begin(void) diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c index 175a0e9a04b6..a1a623c5b069 100644 --- a/arch/arm64/kvm/mmu.c +++ b/arch/arm64/kvm/mmu.c @@ -130,9 +130,21 @@ static void kvm_s2_free_pages_exact(void *virt, size_t size) static struct kvm_pgtable_mm_ops kvm_s2_mm_ops; +static void stage2_free_removed_table_rcu_cb(struct rcu_head *head) +{ + struct page *page = container_of(head, struct page, rcu_head); + void *pgtable = page_to_virt(page); + u32 level = page_private(page); + + kvm_pgtable_stage2_free_removed(&kvm_s2_mm_ops, pgtable, level); +} + static void stage2_free_removed_table(void *addr, u32 level) { - kvm_pgtable_stage2_free_removed(&kvm_s2_mm_ops, addr, level); + struct page *page = virt_to_page(addr); + + set_page_private(page, (unsigned long)level); + call_rcu(&page->rcu_head, stage2_free_removed_table_rcu_cb); } static void kvm_host_get_page(void *addr) -- 2.38.1.273.g43a17bfeac-goog