From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.5 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 297A8C433E0 for ; Wed, 8 Jul 2020 04:43:40 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 8AC7320774 for ; Wed, 8 Jul 2020 04:43:39 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=ellerman.id.au header.i=@ellerman.id.au header.b="jX9pvylY" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8AC7320774 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ellerman.id.au Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from bilbo.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 4B1msP49HYzDr37 for ; Wed, 8 Jul 2020 14:43:37 +1000 (AEST) Received: from ozlabs.org (bilbo.ozlabs.org [IPv6:2401:3900:2:1::2]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4B1mqc4Zq5zDqWW for ; Wed, 8 Jul 2020 14:42:04 +1000 (AEST) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=ellerman.id.au Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=ellerman.id.au header.i=@ellerman.id.au header.a=rsa-sha256 header.s=201909 header.b=jX9pvylY; dkim-atps=neutral Received: from authenticated.ozlabs.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (P-256) server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by mail.ozlabs.org (Postfix) with ESMTPSA id 4B1mqc0y1vz9sDX; Wed, 8 Jul 2020 14:42:04 +1000 (AEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ellerman.id.au; s=201909; t=1594183324; bh=02lvQX5MTs2cs2zT9G3tJXFI/Mphm9oK+EP8lYSqmqc=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=jX9pvylY7D02qxenqdiUhLApQTcintLZX6bbTZXuDsxS9EP3/PfbFAXyXq4LTkkc7 Z0bMhlX2Gy/qHxgbd4OR066tyVI0+kHYn3c5cb3pOV0zGXzgyGjdVxzH/AS2XXRSF9 1w3mEb+QIDqJC2NoAKWyR7MtyavJI4R7K75JUHVnESWlRS7CXYsWfUgYri2WlGB90D YkNoEA/FeEIAuV+XWvzSvAdeeiH7t2pPeIl8jRCCvnQHsS6usH3V95MQJwxT5D9mSo PNHUmewAlL8AiJkyFcnAaBAjqHS/tCy0s7Oqi3IoAmdrhYi00ZOkQH56YBqMh7mVP3 lOKgqwVxqI9FQ== From: Michael Ellerman To: "Aneesh Kumar K.V" , linuxppc-dev@lists.ozlabs.org Subject: Re: [PATCH v2 4/4] powerpc/mm/radix: Create separate mappings for hot-plugged memory In-Reply-To: <20200625064547.228448-5-aneesh.kumar@linux.ibm.com> References: <20200625064547.228448-1-aneesh.kumar@linux.ibm.com> <20200625064547.228448-5-aneesh.kumar@linux.ibm.com> Date: Wed, 08 Jul 2020 14:44:16 +1000 Message-ID: <877dve4nvj.fsf@mpe.ellerman.id.au> MIME-Version: 1.0 Content-Type: text/plain X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "Aneesh Kumar K.V" , Bharata B Rao Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" "Aneesh Kumar K.V" writes: > To enable memory unplug without splitting kernel page table > mapping, we force the max mapping size to the LMB size. LMB > size is the unit in which hypervisor will do memory add/remove > operation. > > This implies on pseries system, we now end up mapping Please expand on why it "implies" that for pseries. > memory with 2M page size instead of 1G. To improve > that we want hypervisor to hint the kernel about the hotplug > memory range. This was added that as part of That > > commit b6eca183e23e ("powerpc/kernel: Enables memory > hot-remove after reboot on pseries guests") > > But we still don't do that on PowerVM. Once we get PowerVM I think you mean PowerVM doesn't provide that hint yet? Realistically it won't until P10. So this means we'll always use 2MB on Power9 PowerVM doesn't it? What about KVM? Have you done any benchmarking on the impact of switching the linear mapping to 2MB pages? > updated, we can then force the 2M mapping only to hot-pluggable > memory region using memblock_is_hotpluggable(). Till then > let's depend on LMB size for finding the mapping page size > for linear range. > > Signed-off-by: Bharata B Rao > Signed-off-by: Aneesh Kumar K.V > --- > arch/powerpc/mm/book3s64/radix_pgtable.c | 83 ++++++++++++++++++++---- > arch/powerpc/platforms/powernv/setup.c | 10 ++- > 2 files changed, 81 insertions(+), 12 deletions(-) > > diff --git a/arch/powerpc/mm/book3s64/radix_pgtable.c b/arch/powerpc/mm/book3s64/radix_pgtable.c > index 78ad11812e0d..a4179e4da49d 100644 > --- a/arch/powerpc/mm/book3s64/radix_pgtable.c > +++ b/arch/powerpc/mm/book3s64/radix_pgtable.c > @@ -15,6 +15,7 @@ > #include > #include > #include > +#include > > #include > #include > @@ -34,6 +35,7 @@ > > unsigned int mmu_pid_bits; > unsigned int mmu_base_pid; > +unsigned int radix_mem_block_size; static? __ro_after_init? > @@ -266,6 +268,7 @@ static unsigned long next_boundary(unsigned long addr, unsigned long end) > > static int __meminit create_physical_mapping(unsigned long start, > unsigned long end, > + unsigned long max_mapping_size, > int nid, pgprot_t _prot) > { > unsigned long vaddr, addr, mapping_size = 0; > @@ -279,6 +282,8 @@ static int __meminit create_physical_mapping(unsigned long start, > int rc; > > gap = next_boundary(addr, end) - addr; > + if (gap > max_mapping_size) > + gap = max_mapping_size; > previous_size = mapping_size; > prev_exec = exec; > > @@ -329,8 +334,9 @@ static void __init radix_init_pgtable(void) > > /* We don't support slb for radix */ > mmu_slb_size = 0; > + > /* > - * Create the linear mapping, using standard page size for now > + * Create the linear mapping > */ > for_each_memblock(memory, reg) { > /* > @@ -346,6 +352,7 @@ static void __init radix_init_pgtable(void) > > WARN_ON(create_physical_mapping(reg->base, > reg->base + reg->size, > + radix_mem_block_size, > -1, PAGE_KERNEL)); > } > > @@ -486,6 +493,49 @@ static int __init radix_dt_scan_page_sizes(unsigned long node, > return 1; > } > > +static int __init probe_memory_block_size(unsigned long node, const char *uname, int > + depth, void *data) > +{ > + const __be32 *block_size; > + int len; > + > + if (depth != 1) > + return 0; > + > + if (!strcmp(uname, "ibm,dynamic-reconfiguration-memory")) { if (strcmp(uname, "ibm,dynamic-reconfiguration-memory") != 0) return 0; Then you can de-indent the rest of the body. > + block_size = of_get_flat_dt_prop(node, "ibm,lmb-size", &len); > + if (!block_size || len < dt_root_size_cells * sizeof(__be32)) This will give us a sparse warning, please do the endian conversion before looking at the value. > + /* > + * Nothing in the device tree > + */ > + return MIN_MEMORY_BLOCK_SIZE; > + > + return dt_mem_next_cell(dt_root_size_cells, &block_size); Just of_read_number() ? This is misusing the return value, as I explained on one of your other recent patches. You should return !0 to indicate that scanning should stop, and the actual value can go via the data pointer, or better just set the global. > + } > + > + return 0; > +} > + > +static unsigned long radix_memory_block_size(void) > +{ > + unsigned long mem_block_size = MIN_MEMORY_BLOCK_SIZE; > + > + if (firmware_has_feature(FW_FEATURE_OPAL)) { > + > + mem_block_size = 1UL * 1024 * 1024 * 1024; We have 1GB hardcoded here and also in pnv_memory_block_size(). Shouldn't pnv_memory_block_size() at least be using radix_mem_block_size? > + } else if (firmware_has_feature(FW_FEATURE_LPAR)) { > + mem_block_size = of_scan_flat_dt(probe_memory_block_size, NULL); > + if (!mem_block_size) > + mem_block_size = MIN_MEMORY_BLOCK_SIZE; > + } > + > + return mem_block_size; > +} It would probably be simpler if that was just inlined below. > + > + > void __init radix__early_init_devtree(void) > { > int rc; > @@ -494,17 +544,27 @@ void __init radix__early_init_devtree(void) > * Try to find the available page sizes in the device-tree > */ > rc = of_scan_flat_dt(radix_dt_scan_page_sizes, NULL); > - if (rc != 0) /* Found */ > - goto found; > + if (rc == 0) { > + /* > + * no page size details found in device tree > + * let's assume we have page 4k and 64k support Capitals and punctuation please? > + */ > + mmu_psize_defs[MMU_PAGE_4K].shift = 12; > + mmu_psize_defs[MMU_PAGE_4K].ap = 0x0; > + > + mmu_psize_defs[MMU_PAGE_64K].shift = 16; > + mmu_psize_defs[MMU_PAGE_64K].ap = 0x5; > + } Moving that seems like an unrelated change. It's a reasonable change but I'd rather you did it in a standalone patch. > /* > - * let's assume we have page 4k and 64k support > + * Max mapping size used when mapping pages. We don't use > + * ppc_md.memory_block_size() here because this get called > + * early and we don't have machine probe called yet. Also > + * the pseries implementation only check for ibm,lmb-size. > + * All hypervisor supporting radix do expose that device > + * tree node. > */ > - mmu_psize_defs[MMU_PAGE_4K].shift = 12; > - mmu_psize_defs[MMU_PAGE_4K].ap = 0x0; > - > - mmu_psize_defs[MMU_PAGE_64K].shift = 16; > - mmu_psize_defs[MMU_PAGE_64K].ap = 0x5; > -found: > + radix_mem_block_size = radix_memory_block_size(); If you did that earlier in the function, before radix_dt_scan_page_sizes(), the logic would be simpler. > return; > } > > @@ -856,7 +916,8 @@ int __meminit radix__create_section_mapping(unsigned long start, > return -1; > } > > - return create_physical_mapping(__pa(start), __pa(end), nid, prot); > + return create_physical_mapping(__pa(start), __pa(end), > + radix_mem_block_size, nid, prot); > } > > int __meminit radix__remove_section_mapping(unsigned long start, unsigned long end) > diff --git a/arch/powerpc/platforms/powernv/setup.c b/arch/powerpc/platforms/powernv/setup.c > index 3bc188da82ba..6e2f614590a3 100644 > --- a/arch/powerpc/platforms/powernv/setup.c > +++ b/arch/powerpc/platforms/powernv/setup.c > @@ -399,7 +399,15 @@ static void pnv_kexec_cpu_down(int crash_shutdown, int secondary) > #ifdef CONFIG_MEMORY_HOTPLUG_SPARSE > static unsigned long pnv_memory_block_size(void) > { > - return 256UL * 1024 * 1024; > + /* > + * We map the kernel linear region with 1GB large pages on radix. For > + * memory hot unplug to work our memory block size must be at least > + * this size. > + */ > + if (radix_enabled()) > + return 1UL * 1024 * 1024 * 1024; > + else > + return 256UL * 1024 * 1024; > } > #endif > > -- > 2.26.2 cheers