On Mon, 21 Feb 2022, Julien Grall wrote: > From: Wei Liu > > The basic idea is like Persistent Kernel Map (PKMAP) in Linux. We > pre-populate all the relevant page tables before the system is fully > set up. > > We will need it on Arm in order to rework the arm64 version of > xenheap_setup_mappings() as we may need to use pages allocated from > the boot allocator before they are effectively mapped. > > This infrastructure is not lock-protected therefore can only be used > before smpboot. After smpboot, map_domain_page() has to be used. > > This is based on the x86 version [1] that was originally implemented > by Wei Liu. > > The PMAP infrastructure is implemented in common code with some > arch helpers to set/clear the page-table entries and convertion > between a fixmap slot to a virtual address... > > As mfn_to_xen_entry() now needs to be exported, take the opportunity > to swich the parameter attr from unsigned to unsigned int. > > [1] > > Signed-off-by: Wei Liu > Signed-off-by: Hongyan Xia > [julien: Adapted for Arm] > Signed-off-by: Julien Grall > > --- > Changes in v3: > - s/BITS_PER_LONG/BITS_PER_BYTE/ > - Move pmap to common code > > Changes in v2: > - New patch > > Cc: Jan Beulich > Cc: Wei Liu > Cc: Andrew Cooper > Cc: Roger Pau Monné > --- > xen/arch/arm/Kconfig | 1 + > xen/arch/arm/include/asm/fixmap.h | 17 +++++++ > xen/arch/arm/include/asm/lpae.h | 8 ++++ > xen/arch/arm/include/asm/pmap.h | 33 +++++++++++++ > xen/arch/arm/mm.c | 7 +-- > xen/common/Kconfig | 3 ++ > xen/common/Makefile | 1 + > xen/common/pmap.c | 79 +++++++++++++++++++++++++++++++ > xen/include/xen/pmap.h | 16 +++++++ > 9 files changed, 159 insertions(+), 6 deletions(-) > create mode 100644 xen/arch/arm/include/asm/pmap.h > create mode 100644 xen/common/pmap.c > create mode 100644 xen/include/xen/pmap.h > > diff --git a/xen/arch/arm/Kconfig b/xen/arch/arm/Kconfig > index ecfa6822e4d3..a89a67802aa9 100644 > --- a/xen/arch/arm/Kconfig > +++ b/xen/arch/arm/Kconfig > @@ -14,6 +14,7 @@ config ARM > select HAS_DEVICE_TREE > select HAS_PASSTHROUGH > select HAS_PDX > + select HAS_PMAP > select IOMMU_FORCE_PT_SHARE > > config ARCH_DEFCONFIG > diff --git a/xen/arch/arm/include/asm/fixmap.h b/xen/arch/arm/include/asm/fixmap.h > index 1cee51e52ab9..c46a15e59de4 100644 > --- a/xen/arch/arm/include/asm/fixmap.h > +++ b/xen/arch/arm/include/asm/fixmap.h > @@ -5,12 +5,20 @@ > #define __ASM_FIXMAP_H > > #include > +#include > > /* Fixmap slots */ > #define FIXMAP_CONSOLE 0 /* The primary UART */ > #define FIXMAP_MISC 1 /* Ephemeral mappings of hardware */ > #define FIXMAP_ACPI_BEGIN 2 /* Start mappings of ACPI tables */ > #define FIXMAP_ACPI_END (FIXMAP_ACPI_BEGIN + NUM_FIXMAP_ACPI_PAGES - 1) /* End mappings of ACPI tables */ > +#define FIXMAP_PMAP_BEGIN (FIXMAP_ACPI_END + 1) /* Start of PMAP */ > +#define FIXMAP_PMAP_END (FIXMAP_PMAP_BEGIN + NUM_FIX_PMAP - 1) /* End of PMAP */ > + > +#define FIXMAP_LAST FIXMAP_PMAP_END > + > +#define FIXADDR_START FIXMAP_ADDR(0) > +#define FIXADDR_TOP FIXMAP_ADDR(FIXMAP_LAST) > > #ifndef __ASSEMBLY__ > > @@ -19,6 +27,15 @@ extern void set_fixmap(unsigned map, mfn_t mfn, unsigned attributes); > /* Remove a mapping from a fixmap entry */ > extern void clear_fixmap(unsigned map); > > +#define fix_to_virt(slot) ((void *)FIXMAP_ADDR(slot)) > + > +static inline unsigned int virt_to_fix(vaddr_t vaddr) > +{ > + BUG_ON(vaddr >= FIXADDR_TOP || vaddr < FIXADDR_START); > + > + return ((vaddr - FIXADDR_START) >> PAGE_SHIFT); > +} > + > #endif /* __ASSEMBLY__ */ > > #endif /* __ASM_FIXMAP_H */ > diff --git a/xen/arch/arm/include/asm/lpae.h b/xen/arch/arm/include/asm/lpae.h > index 8cf932b5c947..6099037da1c0 100644 > --- a/xen/arch/arm/include/asm/lpae.h > +++ b/xen/arch/arm/include/asm/lpae.h > @@ -4,6 +4,7 @@ > #ifndef __ASSEMBLY__ > > #include > +#include > > /* > * WARNING! Unlike the x86 pagetable code, where l1 is the lowest level and > @@ -168,6 +169,13 @@ static inline bool lpae_is_superpage(lpae_t pte, unsigned int level) > third_table_offset(addr) \ > } > > +/* > + * Standard entry type that we'll use to build Xen's own pagetables. > + * We put the same permissions at every level, because they're ignored > + * by the walker in non-leaf entries. > + */ > +lpae_t mfn_to_xen_entry(mfn_t mfn, unsigned int attr); > + > #endif /* __ASSEMBLY__ */ > > /* > diff --git a/xen/arch/arm/include/asm/pmap.h b/xen/arch/arm/include/asm/pmap.h > new file mode 100644 > index 000000000000..70eafe2891d7 > --- /dev/null > +++ b/xen/arch/arm/include/asm/pmap.h > @@ -0,0 +1,33 @@ > +#ifndef __ASM_PMAP_H__ > +#define __ASM_PMAP_H__ > + > +#include > + > +/* XXX: Find an header to declare it */ > +extern lpae_t xen_fixmap[XEN_PT_LPAE_ENTRIES]; Why not fixmap.h? The rest of the ARM stuff looks fine. > +static inline void arch_pmap_map(unsigned int slot, mfn_t mfn) > +{ > + lpae_t *entry = &xen_fixmap[slot]; > + lpae_t pte; > + > + ASSERT(!lpae_is_valid(*entry)); > + > + pte = mfn_to_xen_entry(mfn, PAGE_HYPERVISOR_RW); > + pte.pt.table = 1; > + write_pte(entry, pte); > +} > + > +static inline void arch_pmap_unmap(unsigned int slot) > +{ > + lpae_t pte = {}; > + > + write_pte(&xen_fixmap[slot], pte); > + > + flush_xen_tlb_range_va_local(FIXMAP_ADDR(slot), PAGE_SIZE); > +} > + > +void arch_pmap_map_slot(unsigned int slot, mfn_t mfn); > +void arch_pmap_clear_slot(void *ptr); > + > +#endif /* __ASM_PMAP_H__ */ > diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c > index d6a4b9407c43..b7942464d4de 100644 > --- a/xen/arch/arm/mm.c > +++ b/xen/arch/arm/mm.c > @@ -290,12 +290,7 @@ void dump_hyp_walk(vaddr_t addr) > dump_pt_walk(ttbr, addr, HYP_PT_ROOT_LEVEL, 1); > } > > -/* > - * Standard entry type that we'll use to build Xen's own pagetables. > - * We put the same permissions at every level, because they're ignored > - * by the walker in non-leaf entries. > - */ > -static inline lpae_t mfn_to_xen_entry(mfn_t mfn, unsigned attr) > +lpae_t mfn_to_xen_entry(mfn_t mfn, unsigned int attr) > { > lpae_t e = (lpae_t) { > .pt = { > diff --git a/xen/common/Kconfig b/xen/common/Kconfig > index db687b1785e7..b6c55af2eb03 100644 > --- a/xen/common/Kconfig > +++ b/xen/common/Kconfig > @@ -49,6 +49,9 @@ config HAS_KEXEC > config HAS_PDX > bool > > +config HAS_PMAP > + bool > + > config HAS_SCHED_GRANULARITY > bool > > diff --git a/xen/common/Makefile b/xen/common/Makefile > index ca839118e4d1..8b42b0828134 100644 > --- a/xen/common/Makefile > +++ b/xen/common/Makefile > @@ -28,6 +28,7 @@ obj-y += multicall.o > obj-y += notifier.o > obj-y += page_alloc.o > obj-$(CONFIG_HAS_PDX) += pdx.o > +obj-bin-$(CONFIG_HAS_PMAP) += pmap.init.o > obj-$(CONFIG_PERF_COUNTERS) += perfc.o > obj-y += preempt.o > obj-y += random.o > diff --git a/xen/common/pmap.c b/xen/common/pmap.c > new file mode 100644 > index 000000000000..cea730ead545 > --- /dev/null > +++ b/xen/common/pmap.c > @@ -0,0 +1,79 @@ > +#include > +#include > +#include > + > +#include > +#include > + > +/* > + * Simple mapping infrastructure to map / unmap pages in fixed map. > + * This is used to set up the page table for mapcache, which is used > + * by map domain page infrastructure. > + * > + * This structure is not protected by any locks, so it must not be used after > + * smp bring-up. > + */ > + > +/* Bitmap to track which slot is used */ > +static unsigned long __initdata inuse; > + > +void *__init pmap_map(mfn_t mfn) > +{ > + unsigned long flags; > + unsigned int idx; > + unsigned int slot; > + > + BUILD_BUG_ON(sizeof(inuse) * BITS_PER_BYTE < NUM_FIX_PMAP); > + > + ASSERT(system_state < SYS_STATE_smp_boot); > + > + local_irq_save(flags); > + > + idx = find_first_zero_bit(&inuse, NUM_FIX_PMAP); > + if ( idx == NUM_FIX_PMAP ) > + panic("Out of PMAP slots\n"); > + > + __set_bit(idx, &inuse); > + > + slot = idx + FIXMAP_PMAP_BEGIN; > + ASSERT(slot >= FIXMAP_PMAP_BEGIN && slot <= FIXMAP_PMAP_END); > + > + /* > + * We cannot use set_fixmap() here. We use PMAP when there is no direct map, > + * so map_pages_to_xen() called by set_fixmap() needs to map pages on > + * demand, which then calls pmap() again, resulting in a loop. Modify the > + * PTEs directly instead. The same is true for pmap_unmap(). > + */ > + arch_pmap_map(slot, mfn); > + > + local_irq_restore(flags); > + > + return fix_to_virt(slot); > +} > + > +void __init pmap_unmap(const void *p) > +{ > + unsigned long flags; > + unsigned int idx; > + unsigned int slot = virt_to_fix((unsigned long)p); > + > + ASSERT(system_state < SYS_STATE_smp_boot); > + ASSERT(slot >= FIXMAP_PMAP_BEGIN && slot <= FIXMAP_PMAP_END); > + > + idx = slot - FIXMAP_PMAP_BEGIN; > + local_irq_save(flags); > + > + __clear_bit(idx, &inuse); > + arch_pmap_unmap(slot); > + > + local_irq_restore(flags); > +} > + > +/* > + * Local variables: > + * mode: C > + * c-file-style: "BSD" > + * c-basic-offset: 4 > + * indent-tabs-mode: nil > + * End: > + */ > diff --git a/xen/include/xen/pmap.h b/xen/include/xen/pmap.h > new file mode 100644 > index 000000000000..93e61b10870e > --- /dev/null > +++ b/xen/include/xen/pmap.h > @@ -0,0 +1,16 @@ > +#ifndef __XEN_PMAP_H__ > +#define __XEN_PMAP_H__ > + > +/* Large enough for mapping 5 levels of page tables with some headroom */ > +#define NUM_FIX_PMAP 8 > + > +#ifndef __ASSEMBLY__ > + > +#include > + > +void *pmap_map(mfn_t mfn); > +void pmap_unmap(const void *p); > + > +#endif /* __ASSEMBLY__ */ > + > +#endif /* __XEN_PMAP_H__ */ > -- > 2.32.0 >