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| author | Dan Williams <dan.j.williams@intel.com> | 2019-11-07 04:43:11 +0300 |
|---|---|---|
| committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2019-11-07 17:44:08 +0300 |
| commit | b617c5266eedbef2ccbb90931bb9175faa4ae0bc (patch) | |
| tree | caffea09ec6ac6271f5c3818b1207212a0aa6884 /drivers/firmware/efi/efi.c | |
| parent | 6950e31b35fdf4588cbbdec1813091bb02cf8871 (diff) | |
| download | linux-b617c5266eedbef2ccbb90931bb9175faa4ae0bc.tar.xz | |
efi: Common enable/disable infrastructure for EFI soft reservation
UEFI 2.8 defines an EFI_MEMORY_SP attribute bit to augment the
interpretation of the EFI Memory Types as "reserved for a specific
purpose".
The proposed Linux behavior for specific purpose memory is that it is
reserved for direct-access (device-dax) by default and not available for
any kernel usage, not even as an OOM fallback. Later, through udev
scripts or another init mechanism, these device-dax claimed ranges can
be reconfigured and hot-added to the available System-RAM with a unique
node identifier. This device-dax management scheme implements "soft" in
the "soft reserved" designation by allowing some or all of the
reservation to be recovered as typical memory. This policy can be
disabled at compile-time with CONFIG_EFI_SOFT_RESERVE=n, or runtime with
efi=nosoftreserve.
As for this patch, define the common helpers to determine if the
EFI_MEMORY_SP attribute should be honored. The determination needs to be
made early to prevent the kernel from being loaded into soft-reserved
memory, or otherwise allowing early allocations to land there. Follow-on
changes are needed per architecture to leverage these helpers in their
respective mem-init paths.
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers/firmware/efi/efi.c')
| -rw-r--r-- | drivers/firmware/efi/efi.c | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c index f8f8e273d809..e1cb915b45c6 100644 --- a/drivers/firmware/efi/efi.c +++ b/drivers/firmware/efi/efi.c @@ -81,6 +81,11 @@ bool efi_runtime_disabled(void) return disable_runtime; } +bool __pure __efi_soft_reserve_enabled(void) +{ + return !efi_enabled(EFI_MEM_NO_SOFT_RESERVE); +} + static int __init parse_efi_cmdline(char *str) { if (!str) { @@ -94,6 +99,9 @@ static int __init parse_efi_cmdline(char *str) if (parse_option_str(str, "noruntime")) disable_runtime = true; + if (parse_option_str(str, "nosoftreserve")) + set_bit(EFI_MEM_NO_SOFT_RESERVE, &efi.flags); + return 0; } early_param("efi", parse_efi_cmdline); |