From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail191.messagelabs.com (mail191.messagelabs.com [216.82.242.19]) by kanga.kvack.org (Postfix) with SMTP id 1AD446B004D for ; Mon, 2 Nov 2009 11:18:13 -0500 (EST) Date: Mon, 2 Nov 2009 18:18:09 +0200 From: Gleb Natapov Subject: Re: [PATCH 01/11] Add shared memory hypercall to PV Linux guest. Message-ID: <20091102161809.GG27911@redhat.com> References: <1257076590-29559-1-git-send-email-gleb@redhat.com> <1257076590-29559-2-git-send-email-gleb@redhat.com> <4AEECE2E.2050609@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4AEECE2E.2050609@redhat.com> Sender: owner-linux-mm@kvack.org To: Avi Kivity Cc: kvm@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org List-ID: On Mon, Nov 02, 2009 at 02:18:54PM +0200, Avi Kivity wrote: > On 11/01/2009 01:56 PM, Gleb Natapov wrote: > >Add hypercall that allows guest and host to setup per cpu shared > >memory. > > > > Better to set this up as an MSR (with bit zero enabling, bits 1-5 > features, and 64-byte alignment). This allows auto-reset on INIT > and live migration using the existing MSR save/restore > infrastructure. > Hmm. Will do. > > arch/x86/include/asm/kvm_host.h | 3 + > > arch/x86/include/asm/kvm_para.h | 11 +++++ > > arch/x86/kernel/kvm.c | 82 +++++++++++++++++++++++++++++++++++++++ > > arch/x86/kernel/setup.c | 1 + > > arch/x86/kernel/smpboot.c | 3 + > > arch/x86/kvm/x86.c | 70 +++++++++++++++++++++++++++++++++ > > include/linux/kvm.h | 1 + > > include/linux/kvm_para.h | 4 ++ > > 8 files changed, 175 insertions(+), 0 deletions(-) > > Please separate into guest and host patches. > OK. > >+#define KVM_PV_SHM_VERSION 1 > > versions = bad, feature bits = good > I have both! Do you want me to drop version? > >+ > >+#define KVM_PV_SHM_FEATURES_ASYNC_PF (1<< 0) > >+ > >+struct kvm_vcpu_pv_shm { > >+ __u64 features; > >+ __u64 reason; > >+ __u64 param; > >+}; > >+ > > Some documentation for this? > > Also, the name should reflect the pv pagefault use. For other uses > we can register other areas. > I wanted it to be generic, but I am fine with making it apf specific. It will allow to make it smaller too. > > #define MMU_QUEUE_SIZE 1024 > > > >@@ -37,6 +41,7 @@ struct kvm_para_state { > > }; > > > > static DEFINE_PER_CPU(struct kvm_para_state, para_state); > >+static DEFINE_PER_CPU(struct kvm_vcpu_pv_shm *, kvm_vcpu_pv_shm); > > Easier to put the entire structure here, not a pointer. OK. > > >+ > >+static int kvm_pv_reboot_notify(struct notifier_block *nb, > >+ unsigned long code, void *unused) > >+{ > >+ if (code == SYS_RESTART) > >+ on_each_cpu(kvm_pv_unregister_shm, NULL, 1); > >+ return NOTIFY_DONE; > >+} > >+ > >+static struct notifier_block kvm_pv_reboot_nb = { > >+ .notifier_call = kvm_pv_reboot_notify, > >+}; > > Is this called on kexec, or do we need another hook? > This was added specifically for kexec to work. It was called in my test, > >+static int kvm_pv_setup_shm(struct kvm_vcpu *vcpu, unsigned long gpa, > >+ unsigned long size, unsigned long version, > >+ unsigned long *ret) > >+{ > >+ addr = gfn_to_hva(vcpu->kvm, gfn); > >+ if (kvm_is_error_hva(addr)) > >+ return -EFAULT; > >+ > >+ /* pin page with pv shared memory */ > >+ down_read(&mm->mmap_sem); > >+ r = get_user_pages(current, mm, addr, 1, 1, 0,&vcpu->arch.pv_shm_page, > >+ NULL); > >+ up_read(&mm->mmap_sem); > > This fails if the memory area straddles a page boundary. Aligning Good point. > would solve this. I prefer using put_user() though than a permanent > get_user_pages(). > I want to prevent it from been swapped out. -- Gleb. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org