From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sean Christopherson Date: Thu, 3 Nov 2022 17:53:31 +0000 Subject: [PATCH 39/44] KVM: Drop kvm_count_lock and instead protect kvm_usage_count with kvm_lock In-Reply-To: <7b6ce80e-7f1f-11cd-8bde-8d8fa9fd7e1d@redhat.com> References: <20221102231911.3107438-1-seanjc@google.com> <20221102231911.3107438-40-seanjc@google.com> <7b6ce80e-7f1f-11cd-8bde-8d8fa9fd7e1d@redhat.com> Message-ID: List-Id: To: kvm-riscv@lists.infradead.org MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit On Thu, Nov 03, 2022, Paolo Bonzini wrote: > On 11/3/22 00:19, Sean Christopherson wrote: > > +- kvm_lock is taken outside kvm->mmu_lock > > Not surprising since one is a mutex and one is an rwlock. :) Heh, Signed-off-by: Captain Obvious > You can drop this hunk as well as the "Opportunistically update KVM's locking > documentation" sentence in the commit message. Will do. > > - vcpu->mutex is taken outside kvm->arch.hyperv.hv_lock > > - kvm->arch.mmu_lock is an rwlock. kvm->arch.tdp_mmu_pages_lock and > > @@ -216,15 +220,11 @@ time it will be set using the Dirty tracking mechanism described above. > > :Type: mutex > > :Arch: any > > :Protects: - vm_list > > - > > -``kvm_count_lock`` > > -^^^^^^^^^^^^^^^^^^ > > - > > -:Type: raw_spinlock_t > > -:Arch: any > > -:Protects: - hardware virtualization enable/disable > > -:Comment: 'raw' because hardware enabling/disabling must be atomic /wrt > > - migration. > > + - kvm_usage_count > > + - hardware virtualization enable/disable > > + - module probing (x86 only) > > What do you mean exactly by "module probing"? Is it anything else than what > is serialized by vendor_module_lock? Ooh, I forgot to update this patch after switching to vendor_module_lock. I added the above after fixing the first deadlock between kvm_lock and cpu_hotplug_lock, but later gave up on trying to use kvm_lock after deadlock #2, which is when I when I realized piggybacking kvm_lock was going to be a maintainance nightmare due. 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 CA6CFC433FE for ; Thu, 3 Nov 2022 17:53:40 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 026614B0D7; Thu, 3 Nov 2022 13:53:40 -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=@google.com 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 WsRJXhsIXR7E; Thu, 3 Nov 2022 13:53:38 -0400 (EDT) Received: from mm01.cs.columbia.edu (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id E00914B105; Thu, 3 Nov 2022 13:53:38 -0400 (EDT) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 4BDB64B0D0 for ; Thu, 3 Nov 2022 13:53:38 -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 GATZdjuBvqQf for ; Thu, 3 Nov 2022 13:53:37 -0400 (EDT) Received: from mail-pg1-f171.google.com (mail-pg1-f171.google.com [209.85.215.171]) by mm01.cs.columbia.edu (Postfix) with ESMTPS id 1E1214B0CB for ; Thu, 3 Nov 2022 13:53:37 -0400 (EDT) Received: by mail-pg1-f171.google.com with SMTP id r18so2299844pgr.12 for ; Thu, 03 Nov 2022 10:53:37 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=3tXwq1v6tJCedr2VtV8ELYd8BpIXTKwmGjuY8weIxs8=; b=gjqnoLy192oz/Zxvag+BlBreQGGSfkeJOmpmCEx7rtJpm2GzAgZsoDzOerCZhLAwiY s4s7ScvfoZl8zwg6HI1Ymb7QpOkn2NxzwKs5NTcMl1wbeFQ/hmv3VmCXwSollG4iohk8 ZfCLF4UOQot0TZFoB2ZSgy0wzT2PFfm47J97NCOCE8O1C25eIzJzc1jTDAryWTakKtb6 +QR4ykcFsYtONZVST62uH0g9I4NSfzwB8k/a9JLQz8I+tNs7JhVckzNuFRTBv1+mgFsk IdkM799qrsruF4xx+MeYDtb4Sd8Y4cxbHh++70LJo94wIuv8aLLKYeYlUVyl7mOC3bBK Ww4w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=3tXwq1v6tJCedr2VtV8ELYd8BpIXTKwmGjuY8weIxs8=; b=uu+Bu2Izr6tD06LnXxS/b/nGnMBhzbqdR1Hjcg5JmTKmEpNX90/TjX9Tpf+NM3cWSX 26+zYB0L5mCWDPOobQSZ0wgRMBtouWqp179XSiW59T4gwniNJ37MtEaBn+Jul2EoC2sm ZTfbzVi01HA0Lvx8iGo4Ih9ysNfPW1pohBLCMYT9EH7VDRcgmtld1E5gDUtk7pI5YvNO Ws4u46qtJSr9QAC1uQhSVXU74XnabAZnruAkYki7ErW+hoiuAyERmgIwyQomMoAs/GDF 826LHc5seQ0Kh5WDDayhzFn4CsVaoyFTp4Amx2PR2Oyfoa0Rh9oGBw8izLpVF24ptwks 8g9A== X-Gm-Message-State: ACrzQf2/ldT9hjwBPdMi2taMahHBr8jhS+JlUya8YYrHTroJ8/n8eCpQ fC/8yxYzow8U1rpAJbOE9T9p1g== X-Google-Smtp-Source: AMsMyM5pSkjZTiut6RFho0StQnuo7qAiklz26C63x768BJpOt4UV7sKT8fcspUYyR/B7P1xdFXKPhA== X-Received: by 2002:a05:6a00:999:b0:56c:3d0d:96fe with SMTP id u25-20020a056a00099900b0056c3d0d96femr31657100pfg.12.1667498015565; Thu, 03 Nov 2022 10:53:35 -0700 (PDT) Received: from google.com (7.104.168.34.bc.googleusercontent.com. [34.168.104.7]) by smtp.gmail.com with ESMTPSA id e20-20020a63e014000000b0045ff216a0casm1080329pgh.3.2022.11.03.10.53.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 03 Nov 2022 10:53:35 -0700 (PDT) Date: Thu, 3 Nov 2022 17:53:31 +0000 From: Sean Christopherson To: Paolo Bonzini Subject: Re: [PATCH 39/44] KVM: Drop kvm_count_lock and instead protect kvm_usage_count with kvm_lock Message-ID: References: <20221102231911.3107438-1-seanjc@google.com> <20221102231911.3107438-40-seanjc@google.com> <7b6ce80e-7f1f-11cd-8bde-8d8fa9fd7e1d@redhat.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <7b6ce80e-7f1f-11cd-8bde-8d8fa9fd7e1d@redhat.com> Cc: Matthew Rosato , David Hildenbrand , Yuan Yao , Paul Walmsley , linux-kernel@vger.kernel.org, Michael Ellerman , linux-riscv@lists.infradead.org, Claudio Imbrenda , kvmarm@lists.cs.columbia.edu, linux-s390@vger.kernel.org, Janosch Frank , Marc Zyngier , Huacai Chen , Aleksandar Markovic , Christian Borntraeger , Chao Gao , Eric Farman , Albert Ou , kvm@vger.kernel.org, Atish Patra , kvmarm@lists.linux.dev, Thomas Gleixner , linux-arm-kernel@lists.infradead.org, Isaku Yamahata , Fabiano Rosas , linux-mips@vger.kernel.org, Palmer Dabbelt , kvm-riscv@lists.infradead.org, Vitaly Kuznetsov , linuxppc-dev@lists.ozlabs.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 On Thu, Nov 03, 2022, Paolo Bonzini wrote: > On 11/3/22 00:19, Sean Christopherson wrote: > > +- kvm_lock is taken outside kvm->mmu_lock > > Not surprising since one is a mutex and one is an rwlock. :) Heh, Signed-off-by: Captain Obvious > You can drop this hunk as well as the "Opportunistically update KVM's locking > documentation" sentence in the commit message. Will do. > > - vcpu->mutex is taken outside kvm->arch.hyperv.hv_lock > > - kvm->arch.mmu_lock is an rwlock. kvm->arch.tdp_mmu_pages_lock and > > @@ -216,15 +220,11 @@ time it will be set using the Dirty tracking mechanism described above. > > :Type: mutex > > :Arch: any > > :Protects: - vm_list > > - > > -``kvm_count_lock`` > > -^^^^^^^^^^^^^^^^^^ > > - > > -:Type: raw_spinlock_t > > -:Arch: any > > -:Protects: - hardware virtualization enable/disable > > -:Comment: 'raw' because hardware enabling/disabling must be atomic /wrt > > - migration. > > + - kvm_usage_count > > + - hardware virtualization enable/disable > > + - module probing (x86 only) > > What do you mean exactly by "module probing"? Is it anything else than what > is serialized by vendor_module_lock? Ooh, I forgot to update this patch after switching to vendor_module_lock. I added the above after fixing the first deadlock between kvm_lock and cpu_hotplug_lock, but later gave up on trying to use kvm_lock after deadlock #2, which is when I when I realized piggybacking kvm_lock was going to be a maintainance nightmare due. _______________________________________________ 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 mail-pg1-f179.google.com (mail-pg1-f179.google.com [209.85.215.179]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 45EC763A0 for ; Thu, 3 Nov 2022 17:53:36 +0000 (UTC) Received: by mail-pg1-f179.google.com with SMTP id f63so2333909pgc.2 for ; Thu, 03 Nov 2022 10:53:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=3tXwq1v6tJCedr2VtV8ELYd8BpIXTKwmGjuY8weIxs8=; b=gjqnoLy192oz/Zxvag+BlBreQGGSfkeJOmpmCEx7rtJpm2GzAgZsoDzOerCZhLAwiY s4s7ScvfoZl8zwg6HI1Ymb7QpOkn2NxzwKs5NTcMl1wbeFQ/hmv3VmCXwSollG4iohk8 ZfCLF4UOQot0TZFoB2ZSgy0wzT2PFfm47J97NCOCE8O1C25eIzJzc1jTDAryWTakKtb6 +QR4ykcFsYtONZVST62uH0g9I4NSfzwB8k/a9JLQz8I+tNs7JhVckzNuFRTBv1+mgFsk IdkM799qrsruF4xx+MeYDtb4Sd8Y4cxbHh++70LJo94wIuv8aLLKYeYlUVyl7mOC3bBK Ww4w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=3tXwq1v6tJCedr2VtV8ELYd8BpIXTKwmGjuY8weIxs8=; b=N/ixmfg+E77R2vC5k7aCTa8G55MyAiKIjVnXiELx+6q6OBlyoKz1c7Abnmo1d99QP0 H20ENMru+h+1/0q05IVdtXvBCC1HKBPxwkYd+x0L7xzdD1AhXslh9yzEmhnIzCbfJbM5 Tn2Z7dhM5Mf8isvWali059BhF2Ce7HAIku/syLqQhTfFrSZv+sfi3n1ztH4TlvlQfIZJ wCZtiYo6HOMUa9UIlw6u7koqC+UDhX8LarE4vHDs3Bwg7qNS6aPjbxN6cX7eBrWb/gE7 PSjizkivCIEWDcP8bubnksNORw9ZTsXMlVJtZlBgVHihKFzqupyyoZcxaJQDh8Bsl1yh rT0g== X-Gm-Message-State: ACrzQf32950DBrmX4tL0Mj9Rq1UztoFZ4P3FiWcBzAp0kBqNYAfb8XQD U+6Psd5RsMntIv72h+G23gLHKg== X-Google-Smtp-Source: AMsMyM5pSkjZTiut6RFho0StQnuo7qAiklz26C63x768BJpOt4UV7sKT8fcspUYyR/B7P1xdFXKPhA== X-Received: by 2002:a05:6a00:999:b0:56c:3d0d:96fe with SMTP id u25-20020a056a00099900b0056c3d0d96femr31657100pfg.12.1667498015565; Thu, 03 Nov 2022 10:53:35 -0700 (PDT) Received: from google.com (7.104.168.34.bc.googleusercontent.com. [34.168.104.7]) by smtp.gmail.com with ESMTPSA id e20-20020a63e014000000b0045ff216a0casm1080329pgh.3.2022.11.03.10.53.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 03 Nov 2022 10:53:35 -0700 (PDT) Date: Thu, 3 Nov 2022 17:53:31 +0000 From: Sean Christopherson To: Paolo Bonzini Cc: Marc Zyngier , Huacai Chen , Aleksandar Markovic , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , Matthew Rosato , Eric Farman , Vitaly Kuznetsov , James Morse , Alexandru Elisei , Suzuki K Poulose , Oliver Upton , Atish Patra , David Hildenbrand , kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, kvmarm@lists.cs.columbia.edu, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, Isaku Yamahata , Fabiano Rosas , Michael Ellerman , Chao Gao , Thomas Gleixner , Yuan Yao Subject: Re: [PATCH 39/44] KVM: Drop kvm_count_lock and instead protect kvm_usage_count with kvm_lock Message-ID: References: <20221102231911.3107438-1-seanjc@google.com> <20221102231911.3107438-40-seanjc@google.com> <7b6ce80e-7f1f-11cd-8bde-8d8fa9fd7e1d@redhat.com> Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <7b6ce80e-7f1f-11cd-8bde-8d8fa9fd7e1d@redhat.com> Message-ID: <20221103175331.lSOkwvxFKRGilk-JAki1k3tJ40fddBJZChsN4qFOg68@z> On Thu, Nov 03, 2022, Paolo Bonzini wrote: > On 11/3/22 00:19, Sean Christopherson wrote: > > +- kvm_lock is taken outside kvm->mmu_lock > > Not surprising since one is a mutex and one is an rwlock. :) Heh, Signed-off-by: Captain Obvious > You can drop this hunk as well as the "Opportunistically update KVM's locking > documentation" sentence in the commit message. Will do. > > - vcpu->mutex is taken outside kvm->arch.hyperv.hv_lock > > - kvm->arch.mmu_lock is an rwlock. kvm->arch.tdp_mmu_pages_lock and > > @@ -216,15 +220,11 @@ time it will be set using the Dirty tracking mechanism described above. > > :Type: mutex > > :Arch: any > > :Protects: - vm_list > > - > > -``kvm_count_lock`` > > -^^^^^^^^^^^^^^^^^^ > > - > > -:Type: raw_spinlock_t > > -:Arch: any > > -:Protects: - hardware virtualization enable/disable > > -:Comment: 'raw' because hardware enabling/disabling must be atomic /wrt > > - migration. > > + - kvm_usage_count > > + - hardware virtualization enable/disable > > + - module probing (x86 only) > > What do you mean exactly by "module probing"? Is it anything else than what > is serialized by vendor_module_lock? Ooh, I forgot to update this patch after switching to vendor_module_lock. I added the above after fixing the first deadlock between kvm_lock and cpu_hotplug_lock, but later gave up on trying to use kvm_lock after deadlock #2, which is when I when I realized piggybacking kvm_lock was going to be a maintainance nightmare due. 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 5092CC433FE for ; Thu, 3 Nov 2022 17:53:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=Kmhs3qtEkb64DxXvx9Bk7/9YbA5ng3K42PqO/50k+Wg=; b=zWBAg8bNUgTqT3 exEO1wtUC8xqwi7ntg+RW1ewJzAf7seoydjO7x/RHdpc6SBJw0/197Ies+z6jHaC7KA+UqIu+RSNc F9Dh/4xhTyZkTc6vLK9VK+zCXlZ7Pi+ATtgfx1mWzpaQ61YVYPquL1JUNsQYp0mysyOGniLJepfIc ikreq7ZipDM+zqsEDqkfG04cEzewSrjMwBqOhiOTQJhxlj1RKR611SVAXAHNtfeU4xSznvPspe5z8 Q9QQK6pF9vS6b3k4S4HaACbcn5TjfLj7N2/XxpkJUcIHQQaYQndCfnLQh+vaWo5PGzAoFbggOS6lH 3elFsmm3a+Tx2cv3Hl0w==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1oqePR-0018m1-IL; Thu, 03 Nov 2022 17:53:45 +0000 Received: from mail-pg1-x52a.google.com ([2607:f8b0:4864:20::52a]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1oqePJ-0018ir-D7 for linux-riscv@lists.infradead.org; Thu, 03 Nov 2022 17:53:43 +0000 Received: by mail-pg1-x52a.google.com with SMTP id q71so2307973pgq.8 for ; Thu, 03 Nov 2022 10:53:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=3tXwq1v6tJCedr2VtV8ELYd8BpIXTKwmGjuY8weIxs8=; b=gjqnoLy192oz/Zxvag+BlBreQGGSfkeJOmpmCEx7rtJpm2GzAgZsoDzOerCZhLAwiY s4s7ScvfoZl8zwg6HI1Ymb7QpOkn2NxzwKs5NTcMl1wbeFQ/hmv3VmCXwSollG4iohk8 ZfCLF4UOQot0TZFoB2ZSgy0wzT2PFfm47J97NCOCE8O1C25eIzJzc1jTDAryWTakKtb6 +QR4ykcFsYtONZVST62uH0g9I4NSfzwB8k/a9JLQz8I+tNs7JhVckzNuFRTBv1+mgFsk IdkM799qrsruF4xx+MeYDtb4Sd8Y4cxbHh++70LJo94wIuv8aLLKYeYlUVyl7mOC3bBK Ww4w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=3tXwq1v6tJCedr2VtV8ELYd8BpIXTKwmGjuY8weIxs8=; b=FH7QKIIBhWCVUfwLEtMluRFv3p4EpruJyGVav96imRv8i1YXKuvtJsAZe0DR1bQQpw slsx/u6/XuYoqkw+JWj3dOY2/5a6+8oNHH9+0SYDoZlhFY5CxgbwWv/Txkk2+GiKh3Go NsEBJhbvE2VHXY0xxt6v85iABJKS9ykwsQV5JTIWskVxA8BShnBjm4p8sjiybd/WKESk RoAjnBBFk7qKKFZl99sCwfObITKLcYv/nExk+ps9wv8PTfMYQEewMPTkwJQjHuNt8DV+ h8KF50frjRlpkkCLDlVT9NcjZVDb67Wxv7KV2+eS/qgx6m+KTpI6xH5zTiD0voTM9Ias LqLQ== X-Gm-Message-State: ACrzQf2pDsAIciz6lbdnGLrDTfw54fkQm5xJ+zlkpNHMlWqgS1kZO/I9 TbTuDatJkWMa3l/8SPBTht0aBg== X-Google-Smtp-Source: AMsMyM5pSkjZTiut6RFho0StQnuo7qAiklz26C63x768BJpOt4UV7sKT8fcspUYyR/B7P1xdFXKPhA== X-Received: by 2002:a05:6a00:999:b0:56c:3d0d:96fe with SMTP id u25-20020a056a00099900b0056c3d0d96femr31657100pfg.12.1667498015565; Thu, 03 Nov 2022 10:53:35 -0700 (PDT) Received: from google.com (7.104.168.34.bc.googleusercontent.com. [34.168.104.7]) by smtp.gmail.com with ESMTPSA id e20-20020a63e014000000b0045ff216a0casm1080329pgh.3.2022.11.03.10.53.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 03 Nov 2022 10:53:35 -0700 (PDT) Date: Thu, 3 Nov 2022 17:53:31 +0000 From: Sean Christopherson To: Paolo Bonzini Cc: Marc Zyngier , Huacai Chen , Aleksandar Markovic , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , Matthew Rosato , Eric Farman , Vitaly Kuznetsov , James Morse , Alexandru Elisei , Suzuki K Poulose , Oliver Upton , Atish Patra , David Hildenbrand , kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, kvmarm@lists.cs.columbia.edu, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, Isaku Yamahata , Fabiano Rosas , Michael Ellerman , Chao Gao , Thomas Gleixner , Yuan Yao Subject: Re: [PATCH 39/44] KVM: Drop kvm_count_lock and instead protect kvm_usage_count with kvm_lock Message-ID: References: <20221102231911.3107438-1-seanjc@google.com> <20221102231911.3107438-40-seanjc@google.com> <7b6ce80e-7f1f-11cd-8bde-8d8fa9fd7e1d@redhat.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <7b6ce80e-7f1f-11cd-8bde-8d8fa9fd7e1d@redhat.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20221103_105340_912228_4032BCC2 X-CRM114-Status: GOOD ( 15.33 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org On Thu, Nov 03, 2022, Paolo Bonzini wrote: > On 11/3/22 00:19, Sean Christopherson wrote: > > +- kvm_lock is taken outside kvm->mmu_lock > > Not surprising since one is a mutex and one is an rwlock. :) Heh, Signed-off-by: Captain Obvious > You can drop this hunk as well as the "Opportunistically update KVM's locking > documentation" sentence in the commit message. Will do. > > - vcpu->mutex is taken outside kvm->arch.hyperv.hv_lock > > - kvm->arch.mmu_lock is an rwlock. kvm->arch.tdp_mmu_pages_lock and > > @@ -216,15 +220,11 @@ time it will be set using the Dirty tracking mechanism described above. > > :Type: mutex > > :Arch: any > > :Protects: - vm_list > > - > > -``kvm_count_lock`` > > -^^^^^^^^^^^^^^^^^^ > > - > > -:Type: raw_spinlock_t > > -:Arch: any > > -:Protects: - hardware virtualization enable/disable > > -:Comment: 'raw' because hardware enabling/disabling must be atomic /wrt > > - migration. > > + - kvm_usage_count > > + - hardware virtualization enable/disable > > + - module probing (x86 only) > > What do you mean exactly by "module probing"? Is it anything else than what > is serialized by vendor_module_lock? Ooh, I forgot to update this patch after switching to vendor_module_lock. I added the above after fixing the first deadlock between kvm_lock and cpu_hotplug_lock, but later gave up on trying to use kvm_lock after deadlock #2, which is when I when I realized piggybacking kvm_lock was going to be a maintainance nightmare due. _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv 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 lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id D9E3CC4332F for ; Thu, 3 Nov 2022 17:54:33 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4N3BGc1kJkz3cMv for ; Fri, 4 Nov 2022 04:54:32 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=google.com header.i=@google.com header.a=rsa-sha256 header.s=20210112 header.b=gjqnoLy1; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=google.com (client-ip=2607:f8b0:4864:20::52b; helo=mail-pg1-x52b.google.com; envelope-from=seanjc@google.com; receiver=) Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=google.com header.i=@google.com header.a=rsa-sha256 header.s=20210112 header.b=gjqnoLy1; dkim-atps=neutral Received: from mail-pg1-x52b.google.com (mail-pg1-x52b.google.com [IPv6:2607:f8b0:4864:20::52b]) (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 lists.ozlabs.org (Postfix) with ESMTPS id 4N3BFb71sVz2xH6 for ; Fri, 4 Nov 2022 04:53:38 +1100 (AEDT) Received: by mail-pg1-x52b.google.com with SMTP id e129so2307697pgc.9 for ; Thu, 03 Nov 2022 10:53:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=3tXwq1v6tJCedr2VtV8ELYd8BpIXTKwmGjuY8weIxs8=; b=gjqnoLy192oz/Zxvag+BlBreQGGSfkeJOmpmCEx7rtJpm2GzAgZsoDzOerCZhLAwiY s4s7ScvfoZl8zwg6HI1Ymb7QpOkn2NxzwKs5NTcMl1wbeFQ/hmv3VmCXwSollG4iohk8 ZfCLF4UOQot0TZFoB2ZSgy0wzT2PFfm47J97NCOCE8O1C25eIzJzc1jTDAryWTakKtb6 +QR4ykcFsYtONZVST62uH0g9I4NSfzwB8k/a9JLQz8I+tNs7JhVckzNuFRTBv1+mgFsk IdkM799qrsruF4xx+MeYDtb4Sd8Y4cxbHh++70LJo94wIuv8aLLKYeYlUVyl7mOC3bBK Ww4w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=3tXwq1v6tJCedr2VtV8ELYd8BpIXTKwmGjuY8weIxs8=; b=MbwAtlzfQktMk/VHx7v/544jnH5Zg+prDVpxEfvYYLIbm97WgKBlMq4ohrYC9JU1l2 XADz42wNgxu9KePOgiHx01PALRJvdtc+Vqd9muE6nj/Iy+Q4weL2VrKAsNUG9dDQ6/he sjO3l2B0E59BOycqN/7N48GqCCJCOTlx44SBhpUysp00kLrn8dZkfwg3MP6eXAWLyFh4 CgfShdFA+i5wL1i3Mk7d6dOLWgzr/R1RpH2rVYtU/PJpetLpXKOWQg2sXn9wwT0CyheY hSgerXOnCQJY7fnkkfgicRGIvMxVrO2JDEu+AwXGEQMoCtin+h+pmdh+W6YEB9Ly/b1p LUCg== X-Gm-Message-State: ACrzQf2tSz2jwwKCMpFjk3/dRg/PqxyWrGPxKSaatnzEmyWgoeWCSyL+ eiOfj9QeGuJNKjtvgs7jm+01sQ== X-Google-Smtp-Source: AMsMyM5pSkjZTiut6RFho0StQnuo7qAiklz26C63x768BJpOt4UV7sKT8fcspUYyR/B7P1xdFXKPhA== X-Received: by 2002:a05:6a00:999:b0:56c:3d0d:96fe with SMTP id u25-20020a056a00099900b0056c3d0d96femr31657100pfg.12.1667498015565; Thu, 03 Nov 2022 10:53:35 -0700 (PDT) Received: from google.com (7.104.168.34.bc.googleusercontent.com. [34.168.104.7]) by smtp.gmail.com with ESMTPSA id e20-20020a63e014000000b0045ff216a0casm1080329pgh.3.2022.11.03.10.53.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 03 Nov 2022 10:53:35 -0700 (PDT) Date: Thu, 3 Nov 2022 17:53:31 +0000 From: Sean Christopherson To: Paolo Bonzini Subject: Re: [PATCH 39/44] KVM: Drop kvm_count_lock and instead protect kvm_usage_count with kvm_lock Message-ID: References: <20221102231911.3107438-1-seanjc@google.com> <20221102231911.3107438-40-seanjc@google.com> <7b6ce80e-7f1f-11cd-8bde-8d8fa9fd7e1d@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <7b6ce80e-7f1f-11cd-8bde-8d8fa9fd7e1d@redhat.com> X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Matthew Rosato , David Hildenbrand , Yuan Yao , Paul Walmsley , linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org, Claudio Imbrenda , kvmarm@lists.cs.columbia.edu, linux-s390@vger.kernel.org, Janosch Frank , Marc Zyngier , Huacai Chen , Aleksandar Markovic , James Morse , Christian Borntraeger , Chao Gao , Eric Farman , Albert Ou , Suzuki K Poulose , kvm@vger.kernel.org, Atish Patra , kvmarm@lists.linux.dev, Thomas Gleixner , Alexandru Elisei , linux-arm-kernel@lists.infradead.org, Isaku Yamahata , Fabiano Rosas , linux-mips@vger.kernel.org, Oliver Upton , Palmer Dabbelt , kvm-riscv@lists.infradead.org, Anup Patel , Vitaly Kuznetsov , linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Thu, Nov 03, 2022, Paolo Bonzini wrote: > On 11/3/22 00:19, Sean Christopherson wrote: > > +- kvm_lock is taken outside kvm->mmu_lock > > Not surprising since one is a mutex and one is an rwlock. :) Heh, Signed-off-by: Captain Obvious > You can drop this hunk as well as the "Opportunistically update KVM's locking > documentation" sentence in the commit message. Will do. > > - vcpu->mutex is taken outside kvm->arch.hyperv.hv_lock > > - kvm->arch.mmu_lock is an rwlock. kvm->arch.tdp_mmu_pages_lock and > > @@ -216,15 +220,11 @@ time it will be set using the Dirty tracking mechanism described above. > > :Type: mutex > > :Arch: any > > :Protects: - vm_list > > - > > -``kvm_count_lock`` > > -^^^^^^^^^^^^^^^^^^ > > - > > -:Type: raw_spinlock_t > > -:Arch: any > > -:Protects: - hardware virtualization enable/disable > > -:Comment: 'raw' because hardware enabling/disabling must be atomic /wrt > > - migration. > > + - kvm_usage_count > > + - hardware virtualization enable/disable > > + - module probing (x86 only) > > What do you mean exactly by "module probing"? Is it anything else than what > is serialized by vendor_module_lock? Ooh, I forgot to update this patch after switching to vendor_module_lock. I added the above after fixing the first deadlock between kvm_lock and cpu_hotplug_lock, but later gave up on trying to use kvm_lock after deadlock #2, which is when I when I realized piggybacking kvm_lock was going to be a maintainance nightmare due. 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[34.168.104.7]) by smtp.gmail.com with ESMTPSA id e20-20020a63e014000000b0045ff216a0casm1080329pgh.3.2022.11.03.10.53.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 03 Nov 2022 10:53:35 -0700 (PDT) Date: Thu, 3 Nov 2022 17:53:31 +0000 From: Sean Christopherson To: Paolo Bonzini Cc: Marc Zyngier , Huacai Chen , Aleksandar Markovic , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , Matthew Rosato , Eric Farman , Vitaly Kuznetsov , James Morse , Alexandru Elisei , Suzuki K Poulose , Oliver Upton , Atish Patra , David Hildenbrand , kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, kvmarm@lists.cs.columbia.edu, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, Isaku Yamahata , Fabiano Rosas , Michael Ellerman , Chao Gao , Thomas Gleixner , Yuan Yao Subject: Re: [PATCH 39/44] KVM: Drop kvm_count_lock and instead protect kvm_usage_count with kvm_lock Message-ID: References: <20221102231911.3107438-1-seanjc@google.com> <20221102231911.3107438-40-seanjc@google.com> <7b6ce80e-7f1f-11cd-8bde-8d8fa9fd7e1d@redhat.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <7b6ce80e-7f1f-11cd-8bde-8d8fa9fd7e1d@redhat.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20221103_105340_926970_19F72283 X-CRM114-Status: GOOD ( 16.80 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, Nov 03, 2022, Paolo Bonzini wrote: > On 11/3/22 00:19, Sean Christopherson wrote: > > +- kvm_lock is taken outside kvm->mmu_lock > > Not surprising since one is a mutex and one is an rwlock. :) Heh, Signed-off-by: Captain Obvious > You can drop this hunk as well as the "Opportunistically update KVM's locking > documentation" sentence in the commit message. Will do. > > - vcpu->mutex is taken outside kvm->arch.hyperv.hv_lock > > - kvm->arch.mmu_lock is an rwlock. kvm->arch.tdp_mmu_pages_lock and > > @@ -216,15 +220,11 @@ time it will be set using the Dirty tracking mechanism described above. > > :Type: mutex > > :Arch: any > > :Protects: - vm_list > > - > > -``kvm_count_lock`` > > -^^^^^^^^^^^^^^^^^^ > > - > > -:Type: raw_spinlock_t > > -:Arch: any > > -:Protects: - hardware virtualization enable/disable > > -:Comment: 'raw' because hardware enabling/disabling must be atomic /wrt > > - migration. > > + - kvm_usage_count > > + - hardware virtualization enable/disable > > + - module probing (x86 only) > > What do you mean exactly by "module probing"? Is it anything else than what > is serialized by vendor_module_lock? Ooh, I forgot to update this patch after switching to vendor_module_lock. I added the above after fixing the first deadlock between kvm_lock and cpu_hotplug_lock, but later gave up on trying to use kvm_lock after deadlock #2, which is when I when I realized piggybacking kvm_lock was going to be a maintainance nightmare due. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel