Re: [PATCH 2/5] x86, sleep: always save the value of EFER

Rafael J. Wysocki
2009-11-14T00:15:07Z

On Saturday 14 November 2009, H. Peter Anvin wrote:
> Always save the value of EFER, regardless of the state of NX. Since
> EFER may not actually exist, use rdmsr_safe() to do so.
>
> Signed-off-by: H. Peter Anvin <hpa@zytor.com>
> Cc: Pavel Machek <pavel@ucw.cz>
> Cc: Rafael J. Wysocki <rjw@sisk.pl>

Acked-by: Rafael J. Wysocki <rjw@sisk.pl>

> Cc: Nigel Cunningham <nigel@tuxonice.net>
> ---
> arch/x86/kernel/acpi/sleep.c | 9 +++------
> 1 files changed, 3 insertions(+), 6 deletions(-)
>
> diff --git a/arch/x86/kernel/acpi/sleep.c b/arch/x86/kernel/acpi/sleep.c
> index ca93638..c2e4455 100644
> --- a/arch/x86/kernel/acpi/sleep.c
> +++ b/arch/x86/kernel/acpi/sleep.c
> @@ -78,12 +78,9 @@ int acpi_save_state_mem(void)
> #ifndef CONFIG_64BIT
> store_gdt((struct desc_ptr *)&header->pmode_gdt);
>
> - header->pmode_efer_low = nx_enabled;
> - if (header->pmode_efer_low & 1) {
> - /* This is strange, why not save efer, always? */
> - rdmsr(MSR_EFER, header->pmode_efer_low,
> - header->pmode_efer_high);
> - }
> + header->pmode_efer_low = header->pmode_efer_high = 0;
> + rdmsr_safe(MSR_EFER,
> + &header->pmode_efer_low, &header->pmode_efer_high);
> #endif /* !CONFIG_64BIT */
>
> header->pmode_cr0 = read_cr0();
>