| Message ID | 20221216114853.8227-22-julien@xen.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Remove the directmap | expand |
Hi Julien, > -----Original Message----- > Subject: [PATCH 21/22] xen/arm64: Implement a mapcache for arm64 > > From: Julien Grall <jgrall@amazon.com> > > At the moment, on arm64, map_domain_page() is implemented using > virt_to_mfn(). Therefore it is relying on the directmap. > > In a follow-up patch, we will allow the admin to remove the directmap. > Therefore we want to implement a mapcache. > > Thanksfully there is already one for arm32. So select > ARCH_ARM_DOMAIN_PAGE > and add the necessary boiler plate to support 64-bit: > - The page-table start at level 0, so we need to allocate the level > 1 page-table > - map_domain_page() should check if the page is in the directmap. If > yes, then use virt_to_mfn() to limit the performance impact > when the directmap is still enabled (this will be selectable > on the command line). > > Take the opportunity to replace first_table_offset(...) with offsets[...]. > > Note that, so far, arch_mfns_in_directmap() always return true on Nit: s/return/returns/ > arm64. So the mapcache is not yet used. This will change in a > follow-up patch. > > Signed-off-by: Julien Grall <jgrall@amazon.com> Reviewed-by: Henry Wang <Henry.Wang@arm.com> Kind regards, Henry
On Fri, 16 Dec 2022, Julien Grall wrote: > From: Julien Grall <jgrall@amazon.com> > > At the moment, on arm64, map_domain_page() is implemented using > virt_to_mfn(). Therefore it is relying on the directmap. > > In a follow-up patch, we will allow the admin to remove the directmap. > Therefore we want to implement a mapcache. > > Thanksfully there is already one for arm32. So select ARCH_ARM_DOMAIN_PAGE > and add the necessary boiler plate to support 64-bit: > - The page-table start at level 0, so we need to allocate the level > 1 page-table > - map_domain_page() should check if the page is in the directmap. If > yes, then use virt_to_mfn() to limit the performance impact > when the directmap is still enabled (this will be selectable > on the command line). > > Take the opportunity to replace first_table_offset(...) with offsets[...]. > > Note that, so far, arch_mfns_in_directmap() always return true on > arm64. So the mapcache is not yet used. This will change in a > follow-up patch. > > Signed-off-by: Julien Grall <jgrall@amazon.com> Reviewed-by: Stefano Stabellini <sstabellini@kernel.org> > ---- > > There are a few TODOs: > - It is becoming more critical to fix the mapcache > implementation (this is not compliant with the Arm Arm) > - Evaluate the performance > --- > xen/arch/arm/Kconfig | 1 + > xen/arch/arm/domain_page.c | 47 +++++++++++++++++++++++++++---- > xen/arch/arm/include/asm/config.h | 7 +++++ > xen/arch/arm/include/asm/mm.h | 5 ++++ > xen/arch/arm/mm.c | 6 ++-- > xen/arch/arm/setup.c | 4 +++ > 6 files changed, 62 insertions(+), 8 deletions(-) > > diff --git a/xen/arch/arm/Kconfig b/xen/arch/arm/Kconfig > index 239d3aed3c7f..9c58b2d5c3aa 100644 > --- a/xen/arch/arm/Kconfig > +++ b/xen/arch/arm/Kconfig > @@ -9,6 +9,7 @@ config ARM_64 > select 64BIT > select ARM_EFI > select HAS_FAST_MULTIPLY > + select ARCH_MAP_DOMAIN_PAGE > > config ARM > def_bool y > diff --git a/xen/arch/arm/domain_page.c b/xen/arch/arm/domain_page.c > index 4540b3c5f24c..f3547dc853ef 100644 > --- a/xen/arch/arm/domain_page.c > +++ b/xen/arch/arm/domain_page.c > @@ -1,4 +1,5 @@ > /* SPDX-License-Identifier: GPL-2.0-or-later */ > +#include <xen/domain_page.h> > #include <xen/mm.h> > #include <xen/pmap.h> > #include <xen/vmap.h> > @@ -8,6 +9,8 @@ > /* Override macros from asm/page.h to make them work with mfn_t */ > #undef virt_to_mfn > #define virt_to_mfn(va) _mfn(__virt_to_mfn(va)) > +#undef mfn_to_virt > +#define mfn_to_virt(va) __mfn_to_virt(mfn_x(mfn)) > > /* cpu0's domheap page tables */ > static DEFINE_PAGE_TABLES(cpu0_dommap, DOMHEAP_SECOND_PAGES); > @@ -31,13 +34,30 @@ bool init_domheap_mappings(unsigned int cpu) > { > unsigned int order = get_order_from_pages(DOMHEAP_SECOND_PAGES); > lpae_t *root = per_cpu(xen_pgtable, cpu); > + lpae_t *first; > unsigned int i, first_idx; > lpae_t *domheap; > mfn_t mfn; > > + /* Convenience aliases */ > + DECLARE_OFFSETS(offsets, DOMHEAP_VIRT_START); > + > ASSERT(root); > ASSERT(!per_cpu(xen_dommap, cpu)); > > + /* > + * On Arm64, the root is at level 0. Therefore we need an extra step > + * to allocate the first level page-table. > + */ > +#ifdef CONFIG_ARM_64 > + if ( create_xen_table(&root[offsets[0]]) ) > + return false; > + > + first = xen_map_table(lpae_get_mfn(root[offsets[0]])); > +#else > + first = root; > +#endif > + > /* > * The domheap for cpu0 is initialized before the heap is initialized. > * So we need to use pre-allocated pages. > @@ -58,16 +78,20 @@ bool init_domheap_mappings(unsigned int cpu) > * domheap mapping pages. > */ > mfn = virt_to_mfn(domheap); > - first_idx = first_table_offset(DOMHEAP_VIRT_START); > + first_idx = offsets[1]; > for ( i = 0; i < DOMHEAP_SECOND_PAGES; i++ ) > { > lpae_t pte = mfn_to_xen_entry(mfn_add(mfn, i), MT_NORMAL); > pte.pt.table = 1; > - write_pte(&root[first_idx + i], pte); > + write_pte(&first[first_idx + i], pte); > } > > per_cpu(xen_dommap, cpu) = domheap; > > +#ifdef CONFIG_ARM_64 > + xen_unmap_table(first); > +#endif > + > return true; > } > > @@ -91,6 +115,10 @@ void *map_domain_page(mfn_t mfn) > lpae_t pte; > int i, slot; > > + /* Bypass the mapcache if the page is in the directmap */ > + if ( arch_mfns_in_directmap(mfn_x(mfn), 1) ) > + return mfn_to_virt(mfn); > + > local_irq_save(flags); > > /* The map is laid out as an open-addressed hash table where each > @@ -151,15 +179,24 @@ void *map_domain_page(mfn_t mfn) > } > > /* Release a mapping taken with map_domain_page() */ > -void unmap_domain_page(const void *va) > +void unmap_domain_page(const void *ptr) > { > + unsigned long va = (unsigned long)ptr; > unsigned long flags; > lpae_t *map = this_cpu(xen_dommap); > - int slot = ((unsigned long) va - DOMHEAP_VIRT_START) >> SECOND_SHIFT; > + unsigned int slot; > > - if ( !va ) > + /* > + * map_domain_page() may not have mapped anything if the address > + * is part of the directmap. So ignore anything outside of the > + * domheap. > + */ > + if ( (va < DOMHEAP_VIRT_START) || > + ((va - DOMHEAP_VIRT_START) >= DOMHEAP_VIRT_SIZE) ) > return; > > + slot = (va - DOMHEAP_VIRT_START) >> SECOND_SHIFT; > + > local_irq_save(flags); > > ASSERT(slot >= 0 && slot < DOMHEAP_ENTRIES); > diff --git a/xen/arch/arm/include/asm/config.h b/xen/arch/arm/include/asm/config.h > index 0fefed1b8aa9..12b7f1f1b9ea 100644 > --- a/xen/arch/arm/include/asm/config.h > +++ b/xen/arch/arm/include/asm/config.h > @@ -156,6 +156,13 @@ > #define FRAMETABLE_SIZE GB(32) > #define FRAMETABLE_NR (FRAMETABLE_SIZE / sizeof(*frame_table)) > > +#define DOMHEAP_VIRT_START SLOT0(255) > +#define DOMHEAP_VIRT_SIZE GB(2) > + > +#define DOMHEAP_ENTRIES 1024 /* 1024 2MB mapping slots */ > +/* Number of domheap pagetable pages required at the second level (2MB mappings) */ > +#define DOMHEAP_SECOND_PAGES (DOMHEAP_VIRT_SIZE >> FIRST_SHIFT) > + > #define DIRECTMAP_VIRT_START SLOT0(256) > #define DIRECTMAP_SIZE (SLOT0_ENTRY_SIZE * (265-256)) > #define DIRECTMAP_VIRT_END (DIRECTMAP_VIRT_START + DIRECTMAP_SIZE - 1) > diff --git a/xen/arch/arm/include/asm/mm.h b/xen/arch/arm/include/asm/mm.h > index 7a2c775f9562..d73abf1bf763 100644 > --- a/xen/arch/arm/include/asm/mm.h > +++ b/xen/arch/arm/include/asm/mm.h > @@ -416,6 +416,11 @@ static inline bool arch_has_directmap(void) > return true; > } > > +/* Helpers to allocate, map and unmap a Xen page-table */ > +int create_xen_table(lpae_t *entry); > +lpae_t *xen_map_table(mfn_t mfn); > +void xen_unmap_table(const lpae_t *table); > + > #endif /* __ARCH_ARM_MM__ */ > /* > * Local variables: > diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c > index 2af751af9003..f5fb957554a5 100644 > --- a/xen/arch/arm/mm.c > +++ b/xen/arch/arm/mm.c > @@ -177,7 +177,7 @@ static void __init __maybe_unused build_assertions(void) > #undef CHECK_SAME_SLOT > } > > -static lpae_t *xen_map_table(mfn_t mfn) > +lpae_t *xen_map_table(mfn_t mfn) > { > /* > * During early boot, map_domain_page() may be unusable. Use the > @@ -189,7 +189,7 @@ static lpae_t *xen_map_table(mfn_t mfn) > return map_domain_page(mfn); > } > > -static void xen_unmap_table(const lpae_t *table) > +void xen_unmap_table(const lpae_t *table) > { > /* > * During early boot, xen_map_table() will not use map_domain_page() > @@ -699,7 +699,7 @@ void *ioremap(paddr_t pa, size_t len) > return ioremap_attr(pa, len, PAGE_HYPERVISOR_NOCACHE); > } > > -static int create_xen_table(lpae_t *entry) > +int create_xen_table(lpae_t *entry) > { > mfn_t mfn; > void *p; > diff --git a/xen/arch/arm/setup.c b/xen/arch/arm/setup.c > index 88d9d90fb5ad..b1a8f91bb385 100644 > --- a/xen/arch/arm/setup.c > +++ b/xen/arch/arm/setup.c > @@ -923,6 +923,10 @@ static void __init setup_mm(void) > */ > populate_boot_allocator(); > > + if ( !init_domheap_mappings(smp_processor_id()) ) > + panic("CPU%u: Unable to prepare the domheap page-tables\n", > + smp_processor_id()); > + > total_pages = 0; > > for ( i = 0; i < banks->nr_banks; i++ ) > -- > 2.38.1 >
diff --git a/xen/arch/arm/Kconfig b/xen/arch/arm/Kconfig index 239d3aed3c7f..9c58b2d5c3aa 100644 --- a/xen/arch/arm/Kconfig +++ b/xen/arch/arm/Kconfig @@ -9,6 +9,7 @@ config ARM_64 select 64BIT select ARM_EFI select HAS_FAST_MULTIPLY + select ARCH_MAP_DOMAIN_PAGE config ARM def_bool y diff --git a/xen/arch/arm/domain_page.c b/xen/arch/arm/domain_page.c index 4540b3c5f24c..f3547dc853ef 100644 --- a/xen/arch/arm/domain_page.c +++ b/xen/arch/arm/domain_page.c @@ -1,4 +1,5 @@ /* SPDX-License-Identifier: GPL-2.0-or-later */ +#include <xen/domain_page.h> #include <xen/mm.h> #include <xen/pmap.h> #include <xen/vmap.h> @@ -8,6 +9,8 @@ /* Override macros from asm/page.h to make them work with mfn_t */ #undef virt_to_mfn #define virt_to_mfn(va) _mfn(__virt_to_mfn(va)) +#undef mfn_to_virt +#define mfn_to_virt(va) __mfn_to_virt(mfn_x(mfn)) /* cpu0's domheap page tables */ static DEFINE_PAGE_TABLES(cpu0_dommap, DOMHEAP_SECOND_PAGES); @@ -31,13 +34,30 @@ bool init_domheap_mappings(unsigned int cpu) { unsigned int order = get_order_from_pages(DOMHEAP_SECOND_PAGES); lpae_t *root = per_cpu(xen_pgtable, cpu); + lpae_t *first; unsigned int i, first_idx; lpae_t *domheap; mfn_t mfn; + /* Convenience aliases */ + DECLARE_OFFSETS(offsets, DOMHEAP_VIRT_START); + ASSERT(root); ASSERT(!per_cpu(xen_dommap, cpu)); + /* + * On Arm64, the root is at level 0. Therefore we need an extra step + * to allocate the first level page-table. + */ +#ifdef CONFIG_ARM_64 + if ( create_xen_table(&root[offsets[0]]) ) + return false; + + first = xen_map_table(lpae_get_mfn(root[offsets[0]])); +#else + first = root; +#endif + /* * The domheap for cpu0 is initialized before the heap is initialized. * So we need to use pre-allocated pages. @@ -58,16 +78,20 @@ bool init_domheap_mappings(unsigned int cpu) * domheap mapping pages. */ mfn = virt_to_mfn(domheap); - first_idx = first_table_offset(DOMHEAP_VIRT_START); + first_idx = offsets[1]; for ( i = 0; i < DOMHEAP_SECOND_PAGES; i++ ) { lpae_t pte = mfn_to_xen_entry(mfn_add(mfn, i), MT_NORMAL); pte.pt.table = 1; - write_pte(&root[first_idx + i], pte); + write_pte(&first[first_idx + i], pte); } per_cpu(xen_dommap, cpu) = domheap; +#ifdef CONFIG_ARM_64 + xen_unmap_table(first); +#endif + return true; } @@ -91,6 +115,10 @@ void *map_domain_page(mfn_t mfn) lpae_t pte; int i, slot; + /* Bypass the mapcache if the page is in the directmap */ + if ( arch_mfns_in_directmap(mfn_x(mfn), 1) ) + return mfn_to_virt(mfn); + local_irq_save(flags); /* The map is laid out as an open-addressed hash table where each @@ -151,15 +179,24 @@ void *map_domain_page(mfn_t mfn) } /* Release a mapping taken with map_domain_page() */ -void unmap_domain_page(const void *va) +void unmap_domain_page(const void *ptr) { + unsigned long va = (unsigned long)ptr; unsigned long flags; lpae_t *map = this_cpu(xen_dommap); - int slot = ((unsigned long) va - DOMHEAP_VIRT_START) >> SECOND_SHIFT; + unsigned int slot; - if ( !va ) + /* + * map_domain_page() may not have mapped anything if the address + * is part of the directmap. So ignore anything outside of the + * domheap. + */ + if ( (va < DOMHEAP_VIRT_START) || + ((va - DOMHEAP_VIRT_START) >= DOMHEAP_VIRT_SIZE) ) return; + slot = (va - DOMHEAP_VIRT_START) >> SECOND_SHIFT; + local_irq_save(flags); ASSERT(slot >= 0 && slot < DOMHEAP_ENTRIES); diff --git a/xen/arch/arm/include/asm/config.h b/xen/arch/arm/include/asm/config.h index 0fefed1b8aa9..12b7f1f1b9ea 100644 --- a/xen/arch/arm/include/asm/config.h +++ b/xen/arch/arm/include/asm/config.h @@ -156,6 +156,13 @@ #define FRAMETABLE_SIZE GB(32) #define FRAMETABLE_NR (FRAMETABLE_SIZE / sizeof(*frame_table)) +#define DOMHEAP_VIRT_START SLOT0(255) +#define DOMHEAP_VIRT_SIZE GB(2) + +#define DOMHEAP_ENTRIES 1024 /* 1024 2MB mapping slots */ +/* Number of domheap pagetable pages required at the second level (2MB mappings) */ +#define DOMHEAP_SECOND_PAGES (DOMHEAP_VIRT_SIZE >> FIRST_SHIFT) + #define DIRECTMAP_VIRT_START SLOT0(256) #define DIRECTMAP_SIZE (SLOT0_ENTRY_SIZE * (265-256)) #define DIRECTMAP_VIRT_END (DIRECTMAP_VIRT_START + DIRECTMAP_SIZE - 1) diff --git a/xen/arch/arm/include/asm/mm.h b/xen/arch/arm/include/asm/mm.h index 7a2c775f9562..d73abf1bf763 100644 --- a/xen/arch/arm/include/asm/mm.h +++ b/xen/arch/arm/include/asm/mm.h @@ -416,6 +416,11 @@ static inline bool arch_has_directmap(void) return true; } +/* Helpers to allocate, map and unmap a Xen page-table */ +int create_xen_table(lpae_t *entry); +lpae_t *xen_map_table(mfn_t mfn); +void xen_unmap_table(const lpae_t *table); + #endif /* __ARCH_ARM_MM__ */ /* * Local variables: diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c index 2af751af9003..f5fb957554a5 100644 --- a/xen/arch/arm/mm.c +++ b/xen/arch/arm/mm.c @@ -177,7 +177,7 @@ static void __init __maybe_unused build_assertions(void) #undef CHECK_SAME_SLOT } -static lpae_t *xen_map_table(mfn_t mfn) +lpae_t *xen_map_table(mfn_t mfn) { /* * During early boot, map_domain_page() may be unusable. Use the @@ -189,7 +189,7 @@ static lpae_t *xen_map_table(mfn_t mfn) return map_domain_page(mfn); } -static void xen_unmap_table(const lpae_t *table) +void xen_unmap_table(const lpae_t *table) { /* * During early boot, xen_map_table() will not use map_domain_page() @@ -699,7 +699,7 @@ void *ioremap(paddr_t pa, size_t len) return ioremap_attr(pa, len, PAGE_HYPERVISOR_NOCACHE); } -static int create_xen_table(lpae_t *entry) +int create_xen_table(lpae_t *entry) { mfn_t mfn; void *p; diff --git a/xen/arch/arm/setup.c b/xen/arch/arm/setup.c index 88d9d90fb5ad..b1a8f91bb385 100644 --- a/xen/arch/arm/setup.c +++ b/xen/arch/arm/setup.c @@ -923,6 +923,10 @@ static void __init setup_mm(void) */ populate_boot_allocator(); + if ( !init_domheap_mappings(smp_processor_id()) ) + panic("CPU%u: Unable to prepare the domheap page-tables\n", + smp_processor_id()); + total_pages = 0; for ( i = 0; i < banks->nr_banks; i++ )