Re: [PATCH v5 01/12] x86/paravirt: Move halt paravirt calls under CONFIG_PARAVIRT

Borislav Petkov
2021-08-12T07:17:49Z

On Wed, Aug 04, 2021 at 11:13:18AM -0700, Kuppuswamy Sathyanarayanan wrote:
> From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
>
> CONFIG_PARAVIRT_XXL is mainly defined/used by XEN PV guests. For
> other VM guest types, features supported under CONFIG_PARAVIRT
> are self sufficient. CONFIG_PARAVIRT mainly provides support for
> TLB flush operations and time related operations.
>
> For TDX guest as well, paravirt calls under CONFIG_PARVIRT meets
> most of its requirement except the need of HLT and SAFE_HLT
> paravirt calls, which is currently defined under
> COFNIG_PARAVIRT_XXL.
>
> Since enabling CONFIG_PARAVIRT_XXL is too bloated for TDX guest
> like platforms, move HLT and SAFE_HLT paravirt calls under
> CONFIG_PARAVIRT.
>
> Moving HLT and SAFE_HLT paravirt calls are not fatal and should not
> break any functionality for current users of CONFIG_PARAVIRT.
>
> Co-developed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
> Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> Reviewed-by: Andi Kleen <ak@linux.intel.com>
> Reviewed-by: Tony Luck <tony.luck@intel.com>
> ---

You need to do this before sending your patches:

./scripts/get_maintainer.pl /tmp/tdx.01
Thomas Gleixner <tglx@linutronix.de> (maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT),commit_signer:1/6=17%)
Ingo Molnar <mingo@redhat.com> (maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT))
Borislav Petkov <bp@alien8.de> (maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT),commit_signer:6/6=100%)
x86@kernel.org (maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT))
"H. Peter Anvin" <hpa@zytor.com> (reviewer:X86 ARCHITECTURE (32-BIT AND 64-BIT))
Juergen Gross <jgross@suse.com> (supporter:PARAVIRT_OPS INTERFACE,commit_signer:5/6=83%,authored:5/6=83%,added_lines:15/16=94%,removed_lines:38/39=97%)
Deep Shah <sdeep@vmware.com> (supporter:PARAVIRT_OPS INTERFACE)
"VMware, Inc." <pv-drivers@vmware.com> (supporter:PARAVIRT_OPS INTERFACE)
...

and CC also the supporters - I'm pretty sure at least Juergen would like
to be kept up-to-date on pv changes. I'll CC him and the others now and
leave in the whole diff but make sure you do that in the future please.

> arch/x86/include/asm/irqflags.h | 40 +++++++++++++++------------
> arch/x86/include/asm/paravirt.h | 20 +++++++-------
> arch/x86/include/asm/paravirt_types.h | 3 +-
> arch/x86/kernel/paravirt.c | 4 ++-
> 4 files changed, 36 insertions(+), 31 deletions(-)
>
> diff --git a/arch/x86/include/asm/irqflags.h b/arch/x86/include/asm/irqflags.h
> index c5ce9845c999..f3bb33b1715d 100644
> --- a/arch/x86/include/asm/irqflags.h
> +++ b/arch/x86/include/asm/irqflags.h
> @@ -59,6 +59,28 @@ static inline __cpuidle void native_halt(void)
>
> #endif
>
> +#ifndef CONFIG_PARAVIRT
> +#ifndef __ASSEMBLY__
> +/*
> + * Used in the idle loop; sti takes one instruction cycle
> + * to complete:
> + */
> +static inline __cpuidle void arch_safe_halt(void)
> +{
> + native_safe_halt();
> +}
> +
> +/*
> + * Used when interrupts are already enabled or to
> + * shutdown the processor:
> + */
> +static inline __cpuidle void halt(void)
> +{
> + native_halt();
> +}
> +#endif /* __ASSEMBLY__ */
> +#endif /* CONFIG_PARAVIRT */
> +
> #ifdef CONFIG_PARAVIRT_XXL
> #include <asm/paravirt.h>
> #else
> @@ -80,24 +102,6 @@ static __always_inline void arch_local_irq_enable(void)
> native_irq_enable();
> }
>
> -/*
> - * Used in the idle loop; sti takes one instruction cycle
> - * to complete:
> - */
> -static inline __cpuidle void arch_safe_halt(void)
> -{
> - native_safe_halt();
> -}
> -
> -/*
> - * Used when interrupts are already enabled or to
> - * shutdown the processor:
> - */
> -static inline __cpuidle void halt(void)
> -{
> - native_halt();
> -}
> -
> /*
> * For spinlocks, etc:
> */
> diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h
> index da3a1ac82be5..d323a626c7a8 100644
> --- a/arch/x86/include/asm/paravirt.h
> +++ b/arch/x86/include/asm/paravirt.h
> @@ -97,6 +97,16 @@ static inline void paravirt_arch_exit_mmap(struct mm_struct *mm)
> PVOP_VCALL1(mmu.exit_mmap, mm);
> }
>
> +static inline void arch_safe_halt(void)
> +{
> + PVOP_VCALL0(irq.safe_halt);
> +}
> +
> +static inline void halt(void)
> +{
> + PVOP_VCALL0(irq.halt);
> +}
> +
> #ifdef CONFIG_PARAVIRT_XXL
> static inline void load_sp0(unsigned long sp0)
> {
> @@ -162,16 +172,6 @@ static inline void __write_cr4(unsigned long x)
> PVOP_VCALL1(cpu.write_cr4, x);
> }
>
> -static inline void arch_safe_halt(void)
> -{
> - PVOP_VCALL0(irq.safe_halt);
> -}
> -
> -static inline void halt(void)
> -{
> - PVOP_VCALL0(irq.halt);
> -}
> -
> static inline void wbinvd(void)
> {
> PVOP_ALT_VCALL0(cpu.wbinvd, "wbinvd", ALT_NOT(X86_FEATURE_XENPV));
> diff --git a/arch/x86/include/asm/paravirt_types.h b/arch/x86/include/asm/paravirt_types.h
> index d9d6b0203ec4..40082847f314 100644
> --- a/arch/x86/include/asm/paravirt_types.h
> +++ b/arch/x86/include/asm/paravirt_types.h
> @@ -150,10 +150,9 @@ struct pv_irq_ops {
> struct paravirt_callee_save save_fl;
> struct paravirt_callee_save irq_disable;
> struct paravirt_callee_save irq_enable;
> -
> +#endif
> void (*safe_halt)(void);
> void (*halt)(void);
> -#endif
> } __no_randomize_layout;
>
> struct pv_mmu_ops {
> diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c
> index 04cafc057bed..124e0f6c5d1c 100644
> --- a/arch/x86/kernel/paravirt.c
> +++ b/arch/x86/kernel/paravirt.c
> @@ -283,9 +283,11 @@ struct paravirt_patch_template pv_ops = {
> .irq.save_fl = __PV_IS_CALLEE_SAVE(native_save_fl),
> .irq.irq_disable = __PV_IS_CALLEE_SAVE(native_irq_disable),
> .irq.irq_enable = __PV_IS_CALLEE_SAVE(native_irq_enable),
> +#endif /* CONFIG_PARAVIRT_XXL */
> +
> + /* Irq HLT ops. */

What's that comment for?

> .irq.safe_halt = native_safe_halt,
> .irq.halt = native_halt,
> -#endif /* CONFIG_PARAVIRT_XXL */
>
> /* Mmu ops. */
> .mmu.flush_tlb_user = native_flush_tlb_local,
> --
> 2.25.1
>

--
Regards/Gruss,
Boris.