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b=YCo9ASI2Js2y0lYzH+ndmKVe0VBlFTGkycxT7Zujt14aad9AwhyXNS7KaKggq6hOZ CjqBuMvBipIHRI0dSeAnRaGdIWq9dw+lco9sDto8ytsjwHOsLdjahwZxFEMUyF2PJo rsSN3ldZuKLPl165ORt4ogze7omXIAaPwrKrmNWACeG75cOkrx5NAC189ciVuC4xpg Dh8KVRkGsbWFABrokxiEiOf/Gc1ifElhhLSV1S7Fye8UgqFZ5Ir1yPlX4Yr65gHiyY 28FCxQDb2DcdZ6d5HsyVkKt/PaQmniprxTRaBhweDbGOnULeN9u2tGzvd6gEdrMkEp /B4suKzHDu8yg== From: =?utf-8?B?QmrDtnJuIFTDtnBlbA==?= To: Alexandre Ghiti , Albert Ou , David Hildenbrand , Palmer Dabbelt , Paul Walmsley , linux-riscv@lists.infradead.org, Oscar Salvador Cc: =?utf-8?B?QmrDtnJuIFTDtnBlbA==?= , Andrew Bresticker , Chethan Seshadri , Lorenzo Stoakes , Santosh Mamila , Sivakumar Munnangi , Sunil V L , linux-kernel@vger.kernel.org, linux-mm@kvack.org, virtualization@lists.linux-foundation.org Subject: Re: [PATCH v3 2/9] riscv: mm: Pre-allocate vmemmap/direct map PGD entries In-Reply-To: <20240521114830.841660-3-bjorn@kernel.org> References: <20240521114830.841660-1-bjorn@kernel.org> <20240521114830.841660-3-bjorn@kernel.org> Date: Tue, 21 May 2024 18:09:25 +0200 Message-ID: <87frubdu4q.fsf@all.your.base.are.belong.to.us> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Stat-Signature: xagmh4jexgjqrpurr1bnm99hex87jrsu X-Rspamd-Queue-Id: DB43E18001D X-Rspam-User: X-Rspamd-Server: rspam10 X-HE-Tag: 1716307770-752014 X-HE-Meta: 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 jp4fYrQO m4s1wC/pP4YD5r4t8KiRzxKI8WCYvujPgWsJS1nh5YZih9BcuNkcXW2i6K8qE041RCCmsPHKki/RmFnIauJiFsa5g+gPrZNHzskqnTVf24wMAFNAC5iTyUBsaLibyONlfQkkUa3+f4kDJEoEXvl3tenIDdAi4nEivwXuNiSJwsELqf+d5Q435Sim0Z6I27OmSBB146IRCuc1QHi8+83I9StQDu9Q+Z/lvXwvOcX7Tv4x6laiYfet8elJpuQqh11y4rR/4k2WMKBD5bZnwVVRuFVmDM+0ZY+GSMncZ2RpygOy2Buc4C5nG5LT0OHqWfFrW31LYXihybIOZrzRi5uSPEarekpIhT25eg9E3w0pr2Ujz6qY= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Bj=C3=B6rn T=C3=B6pel writes: > From: Bj=C3=B6rn T=C3=B6pel > > The RISC-V port copies the PGD table from init_mm/swapper_pg_dir to > all userland page tables, which means that if the PGD level table is > changed, other page tables has to be updated as well. > > Instead of having the PGD changes ripple out to all tables, the > synchronization can be avoided by pre-allocating the PGD entries/pages > at boot, avoiding the synchronization all together. > > This is currently done for the bpf/modules, and vmalloc PGD regions. > Extend this scheme for the PGD regions touched by memory hotplugging. > > Prepare the RISC-V port for memory hotplug by pre-allocate > vmemmap/direct map entries at the PGD level. This will roughly waste > ~128 worth of 4K pages when memory hotplugging is enabled in the > kernel configuration. > > Reviewed-by: Alexandre Ghiti > Signed-off-by: Bj=C3=B6rn T=C3=B6pel > --- > arch/riscv/include/asm/kasan.h | 4 ++-- > arch/riscv/mm/init.c | 7 +++++++ > 2 files changed, 9 insertions(+), 2 deletions(-) > > diff --git a/arch/riscv/include/asm/kasan.h b/arch/riscv/include/asm/kasa= n.h > index 0b85e363e778..e6a0071bdb56 100644 > --- a/arch/riscv/include/asm/kasan.h > +++ b/arch/riscv/include/asm/kasan.h > @@ -6,8 +6,6 @@ >=20=20 > #ifndef __ASSEMBLY__ >=20=20 > -#ifdef CONFIG_KASAN > - > /* > * The following comment was copied from arm64: > * KASAN_SHADOW_START: beginning of the kernel virtual addresses. > @@ -34,6 +32,8 @@ > */ > #define KASAN_SHADOW_START ((KASAN_SHADOW_END - KASAN_SHADOW_SIZE) & PGD= IR_MASK) > #define KASAN_SHADOW_END MODULES_LOWEST_VADDR > + > +#ifdef CONFIG_KASAN > #define KASAN_SHADOW_OFFSET _AC(CONFIG_KASAN_SHADOW_OFFSET, UL) >=20=20 > void kasan_init(void); > diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c > index b66f846e7634..c98010ede810 100644 > --- a/arch/riscv/mm/init.c > +++ b/arch/riscv/mm/init.c > @@ -27,6 +27,7 @@ >=20=20 > #include > #include > +#include > #include > #include > #include > @@ -1488,10 +1489,16 @@ static void __init preallocate_pgd_pages_range(un= signed long start, unsigned lon > panic("Failed to pre-allocate %s pages for %s area\n", lvl, area); > } >=20=20 > +#define PAGE_END KASAN_SHADOW_START > + > void __init pgtable_cache_init(void) > { > preallocate_pgd_pages_range(VMALLOC_START, VMALLOC_END, "vmalloc"); > if (IS_ENABLED(CONFIG_MODULES)) > preallocate_pgd_pages_range(MODULES_VADDR, MODULES_END, "bpf/modules"); > + if (IS_ENABLED(CONFIG_MEMORY_HOTPLUG)) { > + preallocate_pgd_pages_range(VMEMMAP_START, VMEMMAP_END, "vmemmap"); > + preallocate_pgd_pages_range(PAGE_OFFSET, PAGE_END, "direct map"); Alex pointed out that KASAN PGDs should be preallocated as well! I'll address this in the next revision. Bj=C3=B6rn