Re: [PATCH 3/3] x86/vsmp: remove vsmp paravirt support

[Juergen Gross]

On 10/08/17 17:28, Shai Fultheim (Shai@xxxxxxxxxxx) wrote:
> NACK.  This is needed and used by thousands of installations.

Okay, thanks for reacting so fast. Will drop the patch.


Juergen

> 
> 
> ________________________________________________________
> Shai Fultheim | M +1 (408) 480-1612 | E Shai@xxxxxxxxxxx
> 
> This email message and any attachments to it are ScaleMP confidential information.
> 
> -----Original Message-----
> From: Ingo Molnar [mailto:mingo.kernel.org@xxxxxxxxx] On Behalf Of Juergen Gross
> Sent: Thursday, August 10, 2017 15:53
> To: linux-kernel@xxxxxxxxxxxxxxx; xen-devel@xxxxxxxxxxxxxxxxxxxx; x86@xxxxxxxxxx
> Cc: hpa@xxxxxxxxx; mingo@xxxxxxxxxx; tglx@xxxxxxxxxxxxx; boris.ostrovsky@xxxxxxxxxx; rusty@xxxxxxxxxxxxxxx; lguest@xxxxxxxxxxxxxxxx; Juergen Gross <jgross@xxxxxxxx>
> Subject: [PATCH 3/3] x86/vsmp: remove vsmp paravirt support
> 
> vSMP has seen its last functional patch more than 3 years ago. It is
> not clear whether the vSMP paravirtualized irq functions are still
> needed.
> 
> Remove them as they seem to be optional and their existence is blocking
> some simplification work of paravirt infrastructure.
> 
> Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
> ---
>  arch/x86/Kconfig          |  1 -
>  arch/x86/kernel/vsmp_64.c | 69 +----------------------------------------------
>  2 files changed, 1 insertion(+), 69 deletions(-)
> 
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index 3fac2570a2e1..13a3d8744ae4 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -495,7 +495,6 @@ config X86_NUMACHIP
>  config X86_VSMP
>  	bool "ScaleMP vSMP"
>  	select HYPERVISOR_GUEST
> -	select PARAVIRT
>  	depends on X86_64 && PCI
>  	depends on X86_EXTENDED_PLATFORM
>  	depends on SMP
> diff --git a/arch/x86/kernel/vsmp_64.c b/arch/x86/kernel/vsmp_64.c
> index b034b1b14b9c..5d392b809ee4 100644
> --- a/arch/x86/kernel/vsmp_64.c
> +++ b/arch/x86/kernel/vsmp_64.c
> @@ -21,7 +21,6 @@
>  #include <asm/apic.h>
>  #include <asm/pci-direct.h>
>  #include <asm/io.h>
> -#include <asm/paravirt.h>
>  #include <asm/setup.h>
>  
>  #define TOPOLOGY_REGISTER_OFFSET 0x10
> @@ -29,64 +28,7 @@
>  /* Flag below is initialized once during vSMP PCI initialization. */
>  static int irq_routing_comply = 1;
>  
> -#if defined CONFIG_PCI && defined CONFIG_PARAVIRT
> -/*
> - * Interrupt control on vSMPowered systems:
> - * ~AC is a shadow of IF.  If IF is 'on' AC should be 'off'
> - * and vice versa.
> - */
> -
> -asmlinkage __visible unsigned long vsmp_save_fl(void)
> -{
> -	unsigned long flags = native_save_fl();
> -
> -	if (!(flags & X86_EFLAGS_IF) || (flags & X86_EFLAGS_AC))
> -		flags &= ~X86_EFLAGS_IF;
> -	return flags;
> -}
> -PV_CALLEE_SAVE_REGS_THUNK(vsmp_save_fl);
> -
> -__visible void vsmp_restore_fl(unsigned long flags)
> -{
> -	if (flags & X86_EFLAGS_IF)
> -		flags &= ~X86_EFLAGS_AC;
> -	else
> -		flags |= X86_EFLAGS_AC;
> -	native_restore_fl(flags);
> -}
> -PV_CALLEE_SAVE_REGS_THUNK(vsmp_restore_fl);
> -
> -asmlinkage __visible void vsmp_irq_disable(void)
> -{
> -	unsigned long flags = native_save_fl();
> -
> -	native_restore_fl((flags & ~X86_EFLAGS_IF) | X86_EFLAGS_AC);
> -}
> -PV_CALLEE_SAVE_REGS_THUNK(vsmp_irq_disable);
> -
> -asmlinkage __visible void vsmp_irq_enable(void)
> -{
> -	unsigned long flags = native_save_fl();
> -
> -	native_restore_fl((flags | X86_EFLAGS_IF) & (~X86_EFLAGS_AC));
> -}
> -PV_CALLEE_SAVE_REGS_THUNK(vsmp_irq_enable);
> -
> -static unsigned __init vsmp_patch(u8 type, u16 clobbers, void *ibuf,
> -				  unsigned long addr, unsigned len)
> -{
> -	switch (type) {
> -	case PARAVIRT_PATCH(pv_irq_ops.irq_enable):
> -	case PARAVIRT_PATCH(pv_irq_ops.irq_disable):
> -	case PARAVIRT_PATCH(pv_irq_ops.save_fl):
> -	case PARAVIRT_PATCH(pv_irq_ops.restore_fl):
> -		return paravirt_patch_default(type, clobbers, ibuf, addr, len);
> -	default:
> -		return native_patch(type, clobbers, ibuf, addr, len);
> -	}
> -
> -}
> -
> +#if defined CONFIG_PCI
>  static void __init set_vsmp_pv_ops(void)
>  {
>  	void __iomem *address;
> @@ -115,15 +57,6 @@ static void __init set_vsmp_pv_ops(void)
>  	}
>  #endif
>  
> -	if (cap & ctl & (1 << 4)) {
> -		/* Setup irq ops and turn on vSMP  IRQ fastpath handling */
> -		pv_irq_ops.irq_disable = PV_CALLEE_SAVE(vsmp_irq_disable);
> -		pv_irq_ops.irq_enable  = PV_CALLEE_SAVE(vsmp_irq_enable);
> -		pv_irq_ops.save_fl  = PV_CALLEE_SAVE(vsmp_save_fl);
> -		pv_irq_ops.restore_fl  = PV_CALLEE_SAVE(vsmp_restore_fl);
> -		pv_init_ops.patch = vsmp_patch;
> -		ctl &= ~(1 << 4);
> -	}
>  	writel(ctl, address + 4);
>  	ctl = readl(address + 4);
>  	pr_info("vSMP CTL: control set to:0x%08x\n", ctl);
>