Re: [PATCH] x86/tlb: Flush global mappings when KAISER is disabled

Paolo Bonzini
2021-03-25T10:53:23Z

On 25/03/21 11:29, Borislav Petkov wrote:
> diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflush.h
> index f5ca15622dc9..2bfa4deb8cae 100644
> --- a/arch/x86/include/asm/tlbflush.h
> +++ b/arch/x86/include/asm/tlbflush.h
> @@ -245,12 +245,15 @@ static inline void __native_flush_tlb_single(unsigned long addr)
> * ASID. But, userspace flushes are probably much more
> * important performance-wise.
> *
> - * Make sure to do only a single invpcid when KAISER is
> - * disabled and we have only a single ASID.
> + * In the KAISER disabled case, do an INVLPG to make sure
> + * the mapping is flushed in case it is a global one.
> */
> - if (kaiser_enabled)
> + if (kaiser_enabled) {
> invpcid_flush_one(X86_CR3_PCID_ASID_USER, addr);
> - invpcid_flush_one(X86_CR3_PCID_ASID_KERN, addr);
> + invpcid_flush_one(X86_CR3_PCID_ASID_KERN, addr);
> + } else {
> + asm volatile("invlpg (%0)" ::"r" (addr) : "memory");
> + }
> }
>
> static inline void __flush_tlb_all(void)
>

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>