On 28/05/2019 11:32, Juergen Gross wrote:
> Instead of dynamically decide whether the previous vcpu was using full
"deciding"
> or default GDT just add a percpu variable for that purpose. This at
"was using a full or default GDT, just add"
> once removes the need for testing vcpu_ids to differ twice.
>
> Cache the need_full_gdt(nd) value in a local variable.
What's the point of doing this? I know the logic is rather complicated
in __context_switch(), but at least it is visually consistent. After
this change, it is asymmetric and harder to follow.
>
> Signed-off-by: Juergen Gross <jgr...@suse.com>
> Reviewed-by: Jan Beulich <jbeul...@suse.com>
> ---
> RFC V2: new patch (split from previous one)
> V1: init percpu flag at cpu startup
> rename variable (Jan Beulich)
> ---
> xen/arch/x86/cpu/common.c | 3 +++
> xen/arch/x86/domain.c | 16 +++++++++++-----
> xen/include/asm-x86/desc.h | 1 +
> 3 files changed, 15 insertions(+), 5 deletions(-)
>
> diff --git a/xen/arch/x86/cpu/common.c b/xen/arch/x86/cpu/common.c
> index 33f5d32557..8b90356fe5 100644
> --- a/xen/arch/x86/cpu/common.c
> +++ b/xen/arch/x86/cpu/common.c
> @@ -49,6 +49,8 @@ unsigned int vaddr_bits __read_mostly = VADDR_BITS;
> static unsigned int cleared_caps[NCAPINTS];
> static unsigned int forced_caps[NCAPINTS];
>
> +DEFINE_PER_CPU(bool, full_gdt_loaded);
> +
> void __init setup_clear_cpu_cap(unsigned int cap)
> {
> const uint32_t *dfs;
> @@ -745,6 +747,7 @@ void load_system_tables(void)
> offsetof(struct tss_struct, __cacheline_filler) - 1,
> SYS_DESC_tss_busy);
>
> + per_cpu(full_gdt_loaded, cpu) = false;
Indentation. (Although I've got half a mind to do a blanket convert of
files like this to Xen style. They are almost completely diverged from
their Linux heritage.)
~Andrew
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