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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [PATCH v3 14/19] xen/arm: add Persistent Map (PMAP) infrastructure
On Mon, 21 Feb 2022, Julien Grall wrote:
> From: Wei Liu <wei.liu2@xxxxxxxxxx>
>
> 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]
> <e92da4ad6015b6089737fcccba3ec1d6424649a5.1588278317.git.hongyxia@xxxxxxxxxx>
>
> Signed-off-by: Wei Liu <wei.liu2@xxxxxxxxxx>
> Signed-off-by: Hongyan Xia <hongyxia@xxxxxxxxxx>
> [julien: Adapted for Arm]
> Signed-off-by: Julien Grall <jgrall@xxxxxxxxxx>
>
> ---
> Changes in v3:
> - s/BITS_PER_LONG/BITS_PER_BYTE/
> - Move pmap to common code
>
> Changes in v2:
> - New patch
>
> Cc: Jan Beulich <jbeulich@xxxxxxxx>
> Cc: Wei Liu <wl@xxxxxxx>
> Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> Cc: Roger Pau Monné <roger.pau@xxxxxxxxxx>
> ---
> 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 <xen/acpi.h>
> +#include <xen/pmap.h>
>
> /* 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 <xen/page-defs.h>
> +#include <xen/mm-frame.h>
>
> /*
> * 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 <xen/mm.h>
> +
> +/* 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 <xen/bitops.h>
> +#include <xen/init.h>
> +#include <xen/pmap.h>
> +
> +#include <asm/pmap.h>
> +#include <asm/fixmap.h>
> +
> +/*
> + * 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 <xen/mm-frame.h>
> +
> +void *pmap_map(mfn_t mfn);
> +void pmap_unmap(const void *p);
> +
> +#endif /* __ASSEMBLY__ */
> +
> +#endif /* __XEN_PMAP_H__ */
> --
> 2.32.0
>
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