Date: Tue, 6 May 2014 08:52:29 -0700 From: Neel Natu <neelnatu@gmail.com> To: Julian Elischer <julian@freebsd.org> Cc: "svn-src-head@freebsd.org" <svn-src-head@freebsd.org>, "svn-src-all@freebsd.org" <svn-src-all@freebsd.org>, "src-committers@freebsd.org" <src-committers@freebsd.org>, Neel Natu <neel@freebsd.org> Subject: Re: svn commit: r265364 - head/sys/amd64/vmm Message-ID: <CAFgRE9EKZKXAfHvsP3kQS3M2PioGFDyRe3ACg9KkD9zsf_Z-GA@mail.gmail.com> In-Reply-To: <536860D3.5030205@freebsd.org> References: <201405051619.s45GJPr6074677@svn.freebsd.org> <536860D3.5030205@freebsd.org>
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Hi Julian, On Mon, May 5, 2014 at 9:10 PM, Julian Elischer <julian@freebsd.org> wrote: > On 5/6/14, 12:19 AM, Neel Natu wrote: >> >> Author: neel >> Date: Mon May 5 16:19:24 2014 >> New Revision: 265364 >> URL: http://svnweb.freebsd.org/changeset/base/265364 >> >> Log: >> Virtual machine halt detection is turned on by default. Allow it to be >> disabled via the tunable 'hw.vmm.halt_detection'. > > So this can only be changed at boot time for the host? not even as a sysctl? The tunable can be set any time before loading vmm.ko: - If you load vmm.ko at boot time then it needs to be set via loader.conf. - If you load vmm.ko after the host is booted then it can be set via kenv(1). > Why is that? It is the easiest way to change the default without any additional complexity. > Why can this not be done from the App? It can be done but I don't think it would be used much. best Neel > >> Modified: >> head/sys/amd64/vmm/vmm.c >> >> Modified: head/sys/amd64/vmm/vmm.c >> >> ============================================================================== >> --- head/sys/amd64/vmm/vmm.c Mon May 5 15:59:31 2014 (r265363) >> +++ head/sys/amd64/vmm/vmm.c Mon May 5 16:19:24 2014 (r265364) >> @@ -189,6 +189,16 @@ static VMM_STAT(VCPU_TOTAL_RUNTIME, "vcp >> SYSCTL_NODE(_hw, OID_AUTO, vmm, CTLFLAG_RW, NULL, NULL); >> +/* >> + * Halt the guest if all vcpus are executing a HLT instruction with >> + * interrupts disabled. >> + */ >> +static int halt_detection_enabled = 1; >> +TUNABLE_INT("hw.vmm.halt_detection", &halt_detection_enabled); >> +SYSCTL_INT(_hw_vmm, OID_AUTO, halt_detection, CTLFLAG_RDTUN, >> + &halt_detection_enabled, 0, >> + "Halt VM if all vcpus execute HLT with interrupts disabled"); >> + >> static int vmm_ipinum; >> SYSCTL_INT(_hw_vmm, OID_AUTO, ipinum, CTLFLAG_RD, &vmm_ipinum, 0, >> "IPI vector used for vcpu notifications"); >> @@ -1047,7 +1057,7 @@ vm_handle_hlt(struct vm *vm, int vcpuid, >> if (intr_disabled) { >> wmesg = "vmhalt"; >> VCPU_CTR0(vm, vcpuid, "Halted"); >> - if (!vcpu_halted) { >> + if (!vcpu_halted && halt_detection_enabled) { >> vcpu_halted = 1; >> CPU_SET_ATOMIC(vcpuid, &vm->halted_cpus); >> } >> >> >> >
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