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[2001:44b8:1113:6700:414:2e33:60ed:75ec]) by smtp.gmail.com with ESMTPSA id g8sm9981404pfo.132.2020.08.04.06.53.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 04 Aug 2020 06:53:19 -0700 (PDT) From: Daniel Axtens To: Mike Rapoport , Andrew Morton Subject: Re: [PATCH v2 01/17] KVM: PPC: Book3S HV: simplify kvm_cma_reserve() In-Reply-To: <20200802163601.8189-2-rppt@kernel.org> References: <20200802163601.8189-1-rppt@kernel.org> <20200802163601.8189-2-rppt@kernel.org> Date: Tue, 04 Aug 2020 23:53:15 +1000 Message-ID: <87tuxio6us.fsf@dja-thinkpad.axtens.net> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200804_095324_327501_3B4D88E6 X-CRM114-Status: GOOD ( 25.59 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Thomas Gleixner , Emil Renner Berthing , linux-sh@vger.kernel.org, Peter Zijlstra , Benjamin Herrenschmidt , Dave Hansen , linux-mips@vger.kernel.org, Max Filippov , Paul Mackerras , sparclinux@vger.kernel.org, linux-riscv@lists.infradead.org, Will Deacon , Christoph Hellwig , Marek Szyprowski , linux-arch@vger.kernel.org, linux-s390@vger.kernel.org, linux-c6x-dev@linux-c6x.org, Baoquan He , Michael Ellerman , x86@kernel.org, Russell King , Mike Rapoport , clang-built-linux@googlegroups.com, Ingo Molnar , linux-arm-kernel@lists.infradead.org, Catalin Marinas , uclinux-h8-devel@lists.sourceforge.jp, linux-xtensa@linux-xtensa.org, openrisc@lists.librecores.org, Borislav Petkov , Andy Lutomirski , Paul Walmsley , Stafford Horne , Hari Bathini , Michal Simek , Yoshinori Sato , linux-mm@kvack.org, linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, Palmer Dabbelt , linuxppc-dev@lists.ozlabs.org, Mike Rapoport Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Mike, > > The memory size calculation in kvm_cma_reserve() traverses memblock.memory > rather than simply call memblock_phys_mem_size(). The comment in that > function suggests that at some point there should have been call to > memblock_analyze() before memblock_phys_mem_size() could be used. > As of now, there is no memblock_analyze() at all and > memblock_phys_mem_size() can be used as soon as cold-plug memory is > registerd with memblock. > > Replace loop over memblock.memory with a call to memblock_phys_mem_size(). > > Signed-off-by: Mike Rapoport > --- > arch/powerpc/kvm/book3s_hv_builtin.c | 11 ++--------- > 1 file changed, 2 insertions(+), 9 deletions(-) > > diff --git a/arch/powerpc/kvm/book3s_hv_builtin.c b/arch/powerpc/kvm/book3s_hv_builtin.c > index 7cd3cf3d366b..56ab0d28de2a 100644 > --- a/arch/powerpc/kvm/book3s_hv_builtin.c > +++ b/arch/powerpc/kvm/book3s_hv_builtin.c > @@ -95,22 +95,15 @@ EXPORT_SYMBOL_GPL(kvm_free_hpt_cma); > void __init kvm_cma_reserve(void) > { > unsigned long align_size; > - struct memblock_region *reg; > - phys_addr_t selected_size = 0; > + phys_addr_t selected_size; > > /* > * We need CMA reservation only when we are in HV mode > */ > if (!cpu_has_feature(CPU_FTR_HVMODE)) > return; > - /* > - * We cannot use memblock_phys_mem_size() here, because > - * memblock_analyze() has not been called yet. > - */ > - for_each_memblock(memory, reg) > - selected_size += memblock_region_memory_end_pfn(reg) - > - memblock_region_memory_base_pfn(reg); > > + selected_size = PHYS_PFN(memblock_phys_mem_size()); > selected_size = (selected_size * kvm_cma_resv_ratio / 100) << PAGE_SHIFT; I think this is correct, but PHYS_PFN does x >> PAGE_SHIFT and then the next line does x << PAGE_SHIFT, so I think we could combine those two lines as: selected_size = PAGE_ALIGN(memblock_phys_mem_size() * kvm_cma_resv_ratio / 100); (I think that might technically change it from aligning down to aligning up but I don't think 1 page matters here.) Kind regards, Daniel > if (selected_size) { > pr_debug("%s: reserving %ld MiB for global area\n", __func__, > -- > 2.26.2 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel