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    SubjectRe: [Part1 PATCH v4 10/17] x86/mm, resource: Use PAGE_KERNEL protection for ioremap of memory pages
    On Sat, Sep 16, 2017 at 07:34:11AM -0500, Brijesh Singh wrote:
    > From: Tom Lendacky <thomas.lendacky@amd.com>
    >
    > In order for memory pages to be properly mapped when SEV is active, we
    > need to use the PAGE_KERNEL protection attribute as the base protection.
    > This will insure that memory mapping of, e.g. ACPI tables, receives the
    > proper mapping attributes.
    >
    > Cc: Thomas Gleixner <tglx@linutronix.de>
    > Cc: Ingo Molnar <mingo@redhat.com>
    > Cc: "H. Peter Anvin" <hpa@zytor.com>
    > Cc: Borislav Petkov <bp@suse.de>
    > Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
    > Cc: Laura Abbott <labbott@redhat.com>
    > Cc: Andy Lutomirski <luto@kernel.org>
    > Cc: "Jérôme Glisse" <jglisse@redhat.com>
    > Cc: Andrew Morton <akpm@linux-foundation.org>
    > Cc: Dan Williams <dan.j.williams@intel.com>
    > Cc: Kees Cook <keescook@chromium.org>
    > Cc: x86@kernel.org
    > Cc: linux-kernel@vger.kernel.org
    > Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
    > Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
    > ---
    > arch/x86/mm/ioremap.c | 77 ++++++++++++++++++++++++++++++++++++++++++--------
    > include/linux/ioport.h | 3 ++
    > kernel/resource.c | 19 +++++++++++++
    > 3 files changed, 88 insertions(+), 11 deletions(-)
    >
    > diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
    > index 52cc0f4ed494..812b8a8066ba 100644
    > --- a/arch/x86/mm/ioremap.c
    > +++ b/arch/x86/mm/ioremap.c
    > @@ -27,6 +27,11 @@
    >
    > #include "physaddr.h"
    >
    > +struct ioremap_mem_flags {
    > + bool system_ram;
    > + bool desc_other;
    > +};
    > +
    > /*
    > * Fix up the linear direct mapping of the kernel to avoid cache attribute
    > * conflicts.
    > @@ -56,19 +61,61 @@ int ioremap_change_attr(unsigned long vaddr, unsigned long size,
    > return err;
    > }
    >
    > -static int __ioremap_check_ram(unsigned long start_pfn, unsigned long nr_pages,
    > - void *arg)
    > +static int __ioremap_check_ram(struct resource *res)
    > {
    > + unsigned long start_pfn, stop_pfn;
    > unsigned long i;
    >
    > - for (i = 0; i < nr_pages; ++i)
    > - if (pfn_valid(start_pfn + i) &&
    > - !PageReserved(pfn_to_page(start_pfn + i)))
    > - return 1;
    > + if ((res->flags & IORESOURCE_SYSTEM_RAM) != IORESOURCE_SYSTEM_RAM)
    > + return 0;
    > +
    > + start_pfn = (res->start + PAGE_SIZE - 1) >> PAGE_SHIFT;
    > + stop_pfn = (res->end + 1) >> PAGE_SHIFT;
    > + if (stop_pfn > start_pfn) {
    > + for (i = 0; i < (stop_pfn - start_pfn); ++i)
    > + if (pfn_valid(start_pfn + i) &&
    > + !PageReserved(pfn_to_page(start_pfn + i)))
    > + return 1;
    > + }
    >
    > return 0;

    Should return bool I guess.

    Btw, this whole resource code is needlessly complex. Trying to follow
    through it is one sick brain-twister. One day someone should go and
    clean up that silly function pointer passing.

    --
    Regards/Gruss,
    Boris.

    SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
    --

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