From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kai Huang Subject: Re: [v2 06/11] vmx: add help functions to support PML Date: Fri, 17 Apr 2015 14:51:41 +0800 Message-ID: <5530AD7D.4020101@linux.intel.com> References: <1429081433-9600-1-git-send-email-kai.huang@linux.intel.com> <1429081433-9600-7-git-send-email-kai.huang@linux.intel.com> <552FF47B0200007800072E23@mail.emea.novell.com> <5530798C.2060108@linux.intel.com> <5530C30D02000078000730D4@mail.emea.novell.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <5530C30D02000078000730D4@mail.emea.novell.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Jan Beulich Cc: andrew.cooper3@citrix.com, kevin.tian@intel.com, tim@xen.org, xen-devel@lists.xen.org List-Id: xen-devel@lists.xenproject.org On 04/17/2015 02:23 PM, Jan Beulich wrote: >>>> On 17.04.15 at 05:10, wrote: >> On 04/16/2015 11:42 PM, Jan Beulich wrote: >>>>>> On 15.04.15 at 09:03, wrote: >>>> +void vmx_vcpu_flush_pml_buffer(struct vcpu *v) >>>> +{ >>>> + uint64_t *pml_buf; >>>> + unsigned long pml_idx; >>>> + >>>> + ASSERT(vmx_vcpu_pml_enabled(v)); >>>> + >>>> + vmx_vmcs_enter(v); >>>> + >>>> + __vmread(GUEST_PML_INDEX, &pml_idx); >>> Don't you require the vCPU to be non-running or current when you >>> get here? If so, perhaps add a respective ASSERT()? >> Yes an ASSERT would be better. >> >> v->pause_count will be increased if vcpu is kicked out by domain_pause >> explicitly, but looks the same thing won't be done if vcpu is kicked out >> by PML buffer full VMEXIT. So should the ASSERT be done like below? >> >> ASSERT(atomic_read(&v->pause_count) || (v == current)); > For one I'd reverse the two parts. And then I think pause count > being non-zero is not a sufficient condition - if a non-synchronous > pause was issued against the vCPU it may still be running. I'd > suggest !vcpu_runnable(v) && !v->is_running, possibly with the > pause count check instead of the runnable one if the only > permitted case where v != current requires the vCPU to be > paused. The vmx_vcpu_flush_pml_buffer is only supposed to be called in below cases: - When PML full VMEXIT happens - In paging_log_dirty_op & hap_track_dirty_vram, before reporting dirty pages to userspace. - In vmx_vcpu_disable_pml, called from vmx_vcpu_destroy, or when log-dirty mode is disabled. In the latter two cases, domain_pause is guaranteed to be called before vmx_vcpu_flush_pml_buffer is called, therefore looks there's no possibility of non-synchronous pause of the vcpu. Or are you suggesting we should suppose this function can be called from any caller, and meanwhile is able to act reasonably? > >>>> + /* >>>> + * Need to change type from log-dirty to normal memory for logged GFN. >>>> + * hap_track_dirty_vram depends on it to work. And we really only need >>>> + * to mark GFNs which hve been successfully changed from log-dirty to >>>> + * normal memory to be dirty. >>>> + */ >>>> + if ( !p2m_change_type_one(v->domain, gfn, p2m_ram_logdirty, >>>> + p2m_ram_rw) ) >>> Indentation. >> To be where exactly? Sorry I didn't find an example to refer in such case. > p2m_ram_rw should align with the v in v->domain. Understood. Will do. Thanks, -Kai > > Jan >