From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail137.messagelabs.com (mail137.messagelabs.com [216.82.249.19]) by kanga.kvack.org (Postfix) with SMTP id 429126B004D for ; Mon, 2 Nov 2009 07:18:57 -0500 (EST) Message-ID: <4AEECE2E.2050609@redhat.com> Date: Mon, 02 Nov 2009 14:18:54 +0200 From: Avi Kivity MIME-Version: 1.0 Subject: Re: [PATCH 01/11] Add shared memory hypercall to PV Linux guest. References: <1257076590-29559-1-git-send-email-gleb@redhat.com> <1257076590-29559-2-git-send-email-gleb@redhat.com> In-Reply-To: <1257076590-29559-2-git-send-email-gleb@redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Gleb Natapov Cc: kvm@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org List-ID: 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. > 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. > +#define KVM_PV_SHM_VERSION 1 > versions = bad, feature bits = good > + > +#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. > #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. > + > +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? > +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 would solve this. I prefer using put_user() though than a permanent get_user_pages(). -- error compiling committee.c: too many arguments to function -- 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