Re: [patch 1/4] x86/paravirt: Dont patch flush_tlb_single

[Josh Poimboeuf]

On Mon, Nov 27, 2017 at 09:34:17PM +0100, Thomas Gleixner wrote:
> native_flush_tlb_single() is not just INLVPG anymore. With
> X86_FEATURE_INVPCID_SINGLE and KAISER enabled it flushes also the shadow
> mapping. But even with KAISER disabled flushing the particular ASID is the
> right thing to do.
> 
> Remove the paravirt patching for it.
> 
> Fixes: 1fde25dc8ef4 ("x86/mm/kaiser: Use PCID feature to make user and kernel switches faster")
> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> ---
>  arch/x86/kernel/paravirt_patch_64.c |    2 --
>  1 file changed, 2 deletions(-)
> 
> --- a/arch/x86/kernel/paravirt_patch_64.c
> +++ b/arch/x86/kernel/paravirt_patch_64.c
> @@ -10,7 +10,6 @@ DEF_NATIVE(pv_irq_ops, save_fl, "pushfq;
>  DEF_NATIVE(pv_mmu_ops, read_cr2, "movq %cr2, %rax");
>  DEF_NATIVE(pv_mmu_ops, read_cr3, "movq %cr3, %rax");
>  DEF_NATIVE(pv_mmu_ops, write_cr3, "movq %rdi, %cr3");
> -DEF_NATIVE(pv_mmu_ops, flush_tlb_single, "invlpg (%rdi)");
>  DEF_NATIVE(pv_cpu_ops, wbinvd, "wbinvd");
>  
>  DEF_NATIVE(pv_cpu_ops, usergs_sysret64, "swapgs; sysretq");
> @@ -60,7 +59,6 @@ unsigned native_patch(u8 type, u16 clobb
>  		PATCH_SITE(pv_mmu_ops, read_cr2);
>  		PATCH_SITE(pv_mmu_ops, read_cr3);
>  		PATCH_SITE(pv_mmu_ops, write_cr3);
> -		PATCH_SITE(pv_mmu_ops, flush_tlb_single);
>  		PATCH_SITE(pv_cpu_ops, wbinvd);
>  #if defined(CONFIG_PARAVIRT_SPINLOCKS)
>  		case PARAVIRT_PATCH(pv_lock_ops.queued_spin_unlock):

Nice find!

Reviewed-and-tested-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>

-- 
Josh