| Message ID | 20240514140446.538622-2-bjorn@kernel.org (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | riscv: Memory Hot(Un)Plug support | expand |
Hi Björn, On Tue, May 14, 2024 at 4:05 PM Björn Töpel <bjorn@kernel.org> wrote: > > From: Björn Töpel <bjorn@rivosinc.com> > > 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. > > Signed-off-by: Björn Töpel <bjorn@rivosinc.com> > --- > 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/kasan.h > index 0b85e363e778..e6a0071bdb56 100644 > --- a/arch/riscv/include/asm/kasan.h > +++ b/arch/riscv/include/asm/kasan.h > @@ -6,8 +6,6 @@ > > #ifndef __ASSEMBLY__ > > -#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) & PGDIR_MASK) > #define KASAN_SHADOW_END MODULES_LOWEST_VADDR > + > +#ifdef CONFIG_KASAN > #define KASAN_SHADOW_OFFSET _AC(CONFIG_KASAN_SHADOW_OFFSET, UL) > > void kasan_init(void); > diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c > index 2574f6a3b0e7..5b8cdfafb52a 100644 > --- a/arch/riscv/mm/init.c > +++ b/arch/riscv/mm/init.c > @@ -27,6 +27,7 @@ > > #include <asm/fixmap.h> > #include <asm/io.h> > +#include <asm/kasan.h> > #include <asm/numa.h> > #include <asm/pgtable.h> > #include <asm/sections.h> > @@ -1488,10 +1489,16 @@ static void __init preallocate_pgd_pages_range(unsigned long start, unsigned lon > panic("Failed to pre-allocate %s pages for %s area\n", lvl, area); > } > > +#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"); > + } > } > #endif > -- > 2.40.1 > As you asked, with https://lore.kernel.org/linux-riscv/20240514133614.87813-1-alexghiti@rivosinc.com/T/#u, you will be able to remove the usage of KASAN_SHADOW_START. But anyhow, you can add: Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com> Thanks, Alex
Alexandre Ghiti <alexghiti@rivosinc.com> writes: > Hi Björn, > > On Tue, May 14, 2024 at 4:05 PM Björn Töpel <bjorn@kernel.org> wrote: >> >> From: Björn Töpel <bjorn@rivosinc.com> >> >> 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. >> >> Signed-off-by: Björn Töpel <bjorn@rivosinc.com> >> --- >> 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/kasan.h >> index 0b85e363e778..e6a0071bdb56 100644 >> --- a/arch/riscv/include/asm/kasan.h >> +++ b/arch/riscv/include/asm/kasan.h >> @@ -6,8 +6,6 @@ >> >> #ifndef __ASSEMBLY__ >> >> -#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) & PGDIR_MASK) >> #define KASAN_SHADOW_END MODULES_LOWEST_VADDR >> + >> +#ifdef CONFIG_KASAN >> #define KASAN_SHADOW_OFFSET _AC(CONFIG_KASAN_SHADOW_OFFSET, UL) >> >> void kasan_init(void); >> diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c >> index 2574f6a3b0e7..5b8cdfafb52a 100644 >> --- a/arch/riscv/mm/init.c >> +++ b/arch/riscv/mm/init.c >> @@ -27,6 +27,7 @@ >> >> #include <asm/fixmap.h> >> #include <asm/io.h> >> +#include <asm/kasan.h> >> #include <asm/numa.h> >> #include <asm/pgtable.h> >> #include <asm/sections.h> >> @@ -1488,10 +1489,16 @@ static void __init preallocate_pgd_pages_range(unsigned long start, unsigned lon >> panic("Failed to pre-allocate %s pages for %s area\n", lvl, area); >> } >> >> +#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"); >> + } >> } >> #endif >> -- >> 2.40.1 >> > > As you asked, with > https://lore.kernel.org/linux-riscv/20240514133614.87813-1-alexghiti@rivosinc.com/T/#u, > you will be able to remove the usage of KASAN_SHADOW_START. Very nice -- consistency! I'll need to respin, so I'll clean this up for the next version. > But anyhow, you can add: > > Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com> Thank you! Björn
diff --git a/arch/riscv/include/asm/kasan.h b/arch/riscv/include/asm/kasan.h index 0b85e363e778..e6a0071bdb56 100644 --- a/arch/riscv/include/asm/kasan.h +++ b/arch/riscv/include/asm/kasan.h @@ -6,8 +6,6 @@ #ifndef __ASSEMBLY__ -#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) & PGDIR_MASK) #define KASAN_SHADOW_END MODULES_LOWEST_VADDR + +#ifdef CONFIG_KASAN #define KASAN_SHADOW_OFFSET _AC(CONFIG_KASAN_SHADOW_OFFSET, UL) void kasan_init(void); diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c index 2574f6a3b0e7..5b8cdfafb52a 100644 --- a/arch/riscv/mm/init.c +++ b/arch/riscv/mm/init.c @@ -27,6 +27,7 @@ #include <asm/fixmap.h> #include <asm/io.h> +#include <asm/kasan.h> #include <asm/numa.h> #include <asm/pgtable.h> #include <asm/sections.h> @@ -1488,10 +1489,16 @@ static void __init preallocate_pgd_pages_range(unsigned long start, unsigned lon panic("Failed to pre-allocate %s pages for %s area\n", lvl, area); } +#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"); + } } #endif