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Miller" , "H. Peter Anvin" , Ingo Molnar , Jann Horn , Juergen Gross , "Liam R. Howlett" , Lorenzo Stoakes , Madhavan Srinivasan , Michael Ellerman , Michal Hocko , Mike Rapoport , Nicholas Piggin , Peter Zijlstra , Ryan Roberts , Suren Baghdasaryan , Thomas Gleixner , Vlastimil Babka , Will Deacon , linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, sparclinux@vger.kernel.org, xen-devel@lists.xenproject.org Subject: Re: [PATCH 4/7] x86/xen: support nested lazy_mmu sections (again) Message-ID: References: <20250904125736.3918646-1-kevin.brodsky@arm.com> <20250904125736.3918646-5-kevin.brodsky@arm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250904125736.3918646-5-kevin.brodsky@arm.com> X-TM-AS-GCONF: 00 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUwODMwMDAzMCBTYWx0ZWRfX5iXkXHtPokV2 s58RZ7e813edv+vWWoqJUrrtWQXbub6NiX58yP1v9mbmzE5GTo4wfrfFkR/YZ/MbCR+iaBSdaCX adCNlkxNA/nEsZ3agSOH3KgEWq38b6wGZtWAzoLq+mKBzCvbn/uEMkBgl3O9f5obeDeeWy94B3P LgKQGohc5o/PIli23EYmnTGZI+Oj8pYgiOworIhg3wrM4u606YHplewCbIn1zTW8AdxtJuUJDYA iMBC7cL5Ca1p2IQg+1kqXYCy73F3DoQq/aCn8/pSszhndcjXi11V8uX0tGswVehF3dhVd7AerLt JrqhsabJDFJw5fzoqnl1EhDRooO7y32BwqH5cYOjZy4q0rOcELXv53bz54YHJ9HbXtIGc4qdlip ckpxcnXd X-Proofpoint-GUID: u6h_butZCR90wxuVu6ifBPi5r4KK37UM X-Proofpoint-ORIG-GUID: HU44fewV-eZEBpYhS3NFrN8FS6mJ4q6n X-Authority-Analysis: v=2.4 cv=Ao/u3P9P c=1 sm=1 tr=0 ts=68bb064f cx=c_pps a=3Bg1Hr4SwmMryq2xdFQyZA==:117 a=3Bg1Hr4SwmMryq2xdFQyZA==:17 a=kj9zAlcOel0A:10 a=yJojWOMRYYMA:10 a=36QzpkCBnVJsay_x71QA:9 a=CjuIK1q_8ugA:10 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1117,Hydra:6.1.9,FMLib:17.12.80.40 definitions=2025-09-05_05,2025-09-04_01,2025-03-28_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 phishscore=0 impostorscore=0 priorityscore=1501 spamscore=0 suspectscore=0 bulkscore=0 adultscore=0 malwarescore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2507300000 definitions=main-2508300030 On Thu, Sep 04, 2025 at 01:57:33PM +0100, Kevin Brodsky wrote: ... > -static void xen_enter_lazy_mmu(void) > +static lazy_mmu_state_t xen_enter_lazy_mmu(void) > { > + if (this_cpu_read(xen_lazy_mode) == XEN_LAZY_MMU) > + return LAZY_MMU_NESTED; > + > enter_lazy(XEN_LAZY_MMU); > + return LAZY_MMU_DEFAULT; > } > > static void xen_flush_lazy_mmu(void) > @@ -2167,11 +2171,12 @@ static void __init xen_post_allocator_init(void) > pv_ops.mmu.write_cr3 = &xen_write_cr3; > } > > -static void xen_leave_lazy_mmu(void) > +static void xen_leave_lazy_mmu(lazy_mmu_state_t state) > { > preempt_disable(); > xen_mc_flush(); > - leave_lazy(XEN_LAZY_MMU); > + if (state != LAZY_MMU_NESTED) > + leave_lazy(XEN_LAZY_MMU); Based on xen_enter_lazy_mmu(), whether this condition needs to be executed with the preemption disabled? Or may be this_cpu_read(xen_lazy_mode) + enter_lazy(XEN_LAZY_MMU) should be executed with the preemption disabled? > preempt_enable(); > } Thanks!