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    SubjectRe: [PATCHv5 06/12] x86/boot/compressed: Handle unaccepted memory
    + mroth
    - brijesh

    On Thu, May 12, 2022 at 10:34:02PM -0700, Dionna Amalie Glaze wrote:
    > Kirill, I've been tracking these changes to see if we can handle the
    > unaccepted memory type for SEV-SNP, but testing has been an issue. The
    > proposed patch in Ovmf to introduce unaccepted memory seems to have
    > stalled out last September
    > (https://www.mail-archive.com/devel@edk2.groups.io/msg35842.html) and
    > is particularly difficult to adapt to SEV-SNP since it doesn't follow
    > the TDVF way of initializing all memory. Is there a different
    > development I might have missed so that we might test these cases?
    > Without the UEFI introducing EFI_UNACCEPTED_MEMORY type, any kernel
    > uses are essentially dead code.
    >
    > Thanks,
    > -Dionna
    >
    > (apologies for repost in text mode)
    >
    > On Tue, May 10, 2022 at 4:04 AM Borislav Petkov <bp@alien8.de> wrote:
    > >
    > > On Fri, May 06, 2022 at 06:30:13PM +0300, Kirill A. Shutemov wrote:
    > > > I find it harder to follow.
    > >
    > > If in doubt, always consider using a helper function:
    > >
    > > ---
    > >
    > > diff --git a/arch/x86/boot/compressed/efi.h b/arch/x86/boot/compressed/efi.h
    > > index 7db2f41b54cd..cf475243b6d5 100644
    > > --- a/arch/x86/boot/compressed/efi.h
    > > +++ b/arch/x86/boot/compressed/efi.h
    > > @@ -32,6 +32,7 @@ typedef struct {
    > > } efi_table_hdr_t;
    > >
    > > #define EFI_CONVENTIONAL_MEMORY 7
    > > +#define EFI_UNACCEPTED_MEMORY 15
    > >
    > > #define EFI_MEMORY_MORE_RELIABLE \
    > > ((u64)0x0000000000010000ULL) /* higher reliability */
    > > diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c
    > > index 28b91df9d31e..39bb4c319dfc 100644
    > > --- a/arch/x86/boot/compressed/kaslr.c
    > > +++ b/arch/x86/boot/compressed/kaslr.c
    > > @@ -671,6 +671,23 @@ static bool process_mem_region(struct mem_vector *region,
    > > }
    > >
    > > #ifdef CONFIG_EFI
    > > +
    > > +/*
    > > + * Only EFI_CONVENTIONAL_MEMORY and EFI_UNACCEPTED_MEMORY (if supported) are guaranteed
    > > + * to be free.
    > > + */
    > > +static inline bool memory_type_is_free(efi_memory_desc_t *md)
    > > +{
    > > + if (md->type == EFI_CONVENTIONAL_MEMORY)
    > > + return true;
    > > +
    > > + if (IS_ENABLED(CONFIG_UNACCEPTED_MEMORY))
    > > + if (md->type == EFI_UNACCEPTED_MEMORY)
    > > + return true;
    > > +
    > > + return false;
    > > +}
    > > +
    > > /*
    > > * Returns true if we processed the EFI memmap, which we prefer over the E820
    > > * table if it is available.
    > > @@ -723,21 +740,9 @@ process_efi_entries(unsigned long minimum, unsigned long image_size)
    > > * free memory and thus available to place the kernel image into,
    > > * but in practice there's firmware where using that memory leads
    > > * to crashes.
    > > - *
    > > - * Only EFI_CONVENTIONAL_MEMORY and EFI_UNACCEPTED_MEMORY (if
    > > - * supported) are guaranteed to be free.
    > > */
    > > -
    > > - switch (md->type) {
    > > - case EFI_CONVENTIONAL_MEMORY:
    > > - break;
    > > - case EFI_UNACCEPTED_MEMORY:
    > > - if (IS_ENABLED(CONFIG_UNACCEPTED_MEMORY))
    > > - break;
    > > + if (!memory_type_is_free(md))
    > > continue;
    > > - default:
    > > - continue;
    > > - }
    > >
    > > if (efi_soft_reserve_enabled() &&
    > > (md->attribute & EFI_MEMORY_SP))
    > > --
    > > Regards/Gruss,
    > > Boris.
    > >
    > > https://people.kernel.org/tglx/notes-about-netiquette
    >
    >
    >
    > --
    > -Dionna Glaze, PhD (she/her)
    >

    --
    Regards/Gruss,
    Boris.

    SUSE Software Solutions Germany GmbH, GF: Ivo Totev, HRB 36809, AG Nürnberg

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