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    SubjectRe: [PATCH 15/16] arm64: Add a helper to retrieve the PTE of a fixmap
    On Thursday 15 Jul 2021 at 17:31:58 (+0100), Marc Zyngier wrote:
    > In order to transfer the early mapping state into KVM's MMIO
    > guard infrastucture, provide a small helper that will retrieve
    > the associated PTE.
    >
    > Signed-off-by: Marc Zyngier <maz@kernel.org>
    > ---
    > arch/arm64/include/asm/fixmap.h | 2 ++
    > arch/arm64/mm/mmu.c | 15 +++++++++++++++
    > 2 files changed, 17 insertions(+)
    >
    > diff --git a/arch/arm64/include/asm/fixmap.h b/arch/arm64/include/asm/fixmap.h
    > index 4335800201c9..1aae625b944f 100644
    > --- a/arch/arm64/include/asm/fixmap.h
    > +++ b/arch/arm64/include/asm/fixmap.h
    > @@ -105,6 +105,8 @@ void __init early_fixmap_init(void);
    >
    > extern void __set_fixmap(enum fixed_addresses idx, phys_addr_t phys, pgprot_t prot);
    >
    > +extern pte_t *__get_fixmap_pte(enum fixed_addresses idx);
    > +
    > #include <asm-generic/fixmap.h>
    >
    > #endif /* !__ASSEMBLY__ */
    > diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
    > index d74586508448..f1b7abd04025 100644
    > --- a/arch/arm64/mm/mmu.c
    > +++ b/arch/arm64/mm/mmu.c
    > @@ -1286,6 +1286,21 @@ void __set_fixmap(enum fixed_addresses idx,
    > }
    > }
    >
    > +pte_t *__get_fixmap_pte(enum fixed_addresses idx)
    > +{
    > + unsigned long addr = __fix_to_virt(idx);

    Nit: odd spacing here.

    > + pte_t *ptep;
    > +
    > + BUG_ON(idx <= FIX_HOLE || idx >= __end_of_fixed_addresses);
    > +
    > + ptep = fixmap_pte(addr);
    > +
    > + if (!pte_valid(*ptep))
    > + return NULL;
    > +
    > + return ptep;
    > +}
    > +
    > void *__init fixmap_remap_fdt(phys_addr_t dt_phys, int *size, pgprot_t prot)
    > {
    > const u64 dt_virt_base = __fix_to_virt(FIX_FDT);
    > --
    > 2.30.2
    >

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