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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v3 1/8] xen/arm: introduce early_ioremap
On Tue, 2012-12-18 at 18:46 +0000, Stefano Stabellini wrote:
> Introduce a function to map a range of physical memory into Xen virtual
> memory.
> It doesn't need domheap to be setup.
> It is going to be used to map the videoram.
>
> Add flush_xen_data_tlb_range, that flushes a range of virtual addresses.
>
> Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
> ---
> xen/arch/arm/mm.c | 32 ++++++++++++++++++++++++++++++++
> xen/include/asm-arm/config.h | 2 ++
> xen/include/asm-arm/mm.h | 3 ++-
> xen/include/asm-arm/page.h | 23 +++++++++++++++++++++++
> 4 files changed, 59 insertions(+), 1 deletions(-)
>
> diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c
> index 855f83d..0d7a163 100644
> --- a/xen/arch/arm/mm.c
> +++ b/xen/arch/arm/mm.c
> @@ -367,6 +367,38 @@ void __init setup_frametable_mappings(paddr_t ps,
> paddr_t pe)
> frametable_virt_end = FRAMETABLE_VIRT_START + (nr_pages * sizeof(struct
> page_info));
> }
>
> +/* Map the physical memory range start - start + len into virtual
> + * memory and return the virtual address of the mapping.
> + * start has to be 2MB aligned.
> + * len has to be < EARLY_VMAP_END - EARLY_VMAP_START.
> + */
> +void* early_ioremap(paddr_t start, size_t len, unsigned attributes)
Should be __init I think, to discourage its use later on. If when we
need that they proper vmap+ioremap should be implemented.
> +{
> + static unsigned long virt_start = EARLY_VMAP_START;
Is the idea that if/when we implement proper vmap + ioremap support we
should initialise the vmap area with EARLY_VMAP_START..virt_start
already assigned and virt_start..EARLY_VMAP_END free (removing all the
EARLY_ I guess)?
At some point I suppose we will need to integrate this with
xen/common/vmap.c.
> + void* ret_addr = (void *)virt_start;
> + paddr_t end = start + len;
> +
> + ASSERT(!(start & (~SECOND_MASK)));
> + ASSERT(!(virt_start & (~SECOND_MASK)));
> +
> + /* The range we need to map is too big */
> + if ( virt_start + len >= EARLY_VMAP_END )
> + return NULL;
> +
> + while ( start < end )
> + {
> + lpae_t e = mfn_to_xen_entry(start >> PAGE_SHIFT);
> + e.pt.ai = attributes;
> + write_pte(xen_second + second_table_offset(virt_start), e);
> +
> + start += SECOND_SIZE;
> + virt_start += SECOND_SIZE;
> + }
> + flush_xen_data_tlb_range((unsigned long) ret_addr, len);
Just cast this in the return? At the moment you cast to void* only to
cast it back to unsigned long.
> +
> + return ret_addr;
> +}
> +
> enum mg { mg_clear, mg_ro, mg_rw, mg_rx };
> static void set_pte_flags_on_range(const char *p, unsigned long l, enum mg
> mg)
> {
> diff --git a/xen/include/asm-arm/config.h b/xen/include/asm-arm/config.h
> index 2a05539..87db0d1 100644
> --- a/xen/include/asm-arm/config.h
> +++ b/xen/include/asm-arm/config.h
> @@ -73,9 +73,11 @@
> #define FIXMAP_ADDR(n) (mk_unsigned_long(0x00400000) + (n) *
> PAGE_SIZE)
> #define BOOT_MISC_VIRT_START mk_unsigned_long(0x00600000)
> #define FRAMETABLE_VIRT_START mk_unsigned_long(0x02000000)
> +#define EARLY_VMAP_START mk_unsigned_long(0x10000000)
There is a comment right above here which describes Xen virtual memory
layout, this needs updating as Tim requested before.
Also the convention is FOO_VIRT_START.
> #define XENHEAP_VIRT_START mk_unsigned_long(0x40000000)
> #define DOMHEAP_VIRT_START mk_unsigned_long(0x80000000)
>
> +#define EARLY_VMAP_END XENHEAP_VIRT_START
> #define HYPERVISOR_VIRT_START XEN_VIRT_START
>
> #define DOMHEAP_ENTRIES 1024 /* 1024 2MB mapping slots */
> diff --git a/xen/include/asm-arm/mm.h b/xen/include/asm-arm/mm.h
> index e95ece1..4ed5df6 100644
> --- a/xen/include/asm-arm/mm.h
> +++ b/xen/include/asm-arm/mm.h
> @@ -150,7 +150,8 @@ extern void setup_frametable_mappings(paddr_t ps, paddr_t
> pe);
> extern void set_fixmap(unsigned map, unsigned long mfn, unsigned attributes);
> /* Remove a mapping from a fixmap entry */
> extern void clear_fixmap(unsigned map);
> -
> +/* map a 2MB aligned physical range in virtual memory. */
> +void* early_ioremap(paddr_t start, size_t len, unsigned attributes);
>
> #define mfn_valid(mfn) ({
> \
> unsigned long __m_f_n = (mfn);
> \
> diff --git a/xen/include/asm-arm/page.h b/xen/include/asm-arm/page.h
> index d89261e..0790dda 100644
> --- a/xen/include/asm-arm/page.h
> +++ b/xen/include/asm-arm/page.h
> @@ -328,6 +328,23 @@ static inline void flush_xen_data_tlb_va(unsigned long
> va)
> : : "r" (va) : "memory");
> }
>
> +/*
> + * Flush a range of VA's hypervisor mappings from the data TLB. This is not
> + * sufficient when changing code mappings or for self modifying code.
> + */
> +static inline void flush_xen_data_tlb_range(unsigned long va, unsigned long
> size)
> +{
> + unsigned long end = va + size;
> + while ( va < end ) {
> + asm volatile("dsb;" /* Ensure preceding are visible */
Either this dsb should be on the next line (aligned with the following
lines) or the following lines should be indented further to match (we
have both styles in this file, but lets not have a 3rd).
Although it would probably be better to just call flush_xen_data_tlb_va
here?
Function should be flush_xen_data_tlb_range_va I think. I'm not sure it
is worth a new function though, perhaps just add size to the existing
flush_xen_data_tlb_va, there's not too many callers?
While I was grepping I noticed flush_xen_data_tlb_va(dest_va) in
setup_pagetables(). dest_va has just been setup with a second level (2M
mapping). Is it not a bit dodgy to only flush the first 4K of that?
> + STORE_CP32(0, TLBIMVAH)
> + "dsb;" /* Ensure completion of the TLB flush */
> + "isb;"
> + : : "r" (va) : "memory");
> + va += PAGE_SIZE;
> + }
> +}
> +
> /* Flush all non-hypervisor mappings from the TLB */
> static inline void flush_guest_tlb(void)
> {
> @@ -418,8 +435,14 @@ static inline uint64_t gva_to_ipa(uint32_t va)
> #define LPAE_ENTRY_MASK (LPAE_ENTRIES - 1)
>
> #define THIRD_SHIFT PAGE_SHIFT
> +#define THIRD_SIZE (1u << THIRD_SHIFT)
> +#define THIRD_MASK (~(THIRD_SIZE - 1))
> #define SECOND_SHIFT (THIRD_SHIFT + LPAE_SHIFT)
> +#define SECOND_SIZE (1u << SECOND_SHIFT)
> +#define SECOND_MASK (~(SECOND_SIZE - 1))
> #define FIRST_SHIFT (SECOND_SHIFT + LPAE_SHIFT)
> +#define FIRST_SIZE (1u << FIRST_SHIFT)
> +#define FIRST_MASK (~(FIRST_SIZE - 1))
Whitespace is off here.
>
> /* Calculate the offsets into the pagetables for a given VA */
> #define first_linear_offset(va) (va >> FIRST_SHIFT)
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