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Message-ID: <a8f2ac8e-45dc-1c12-e888-6ad880b1306f@scalemp.com>
Date: Thu, 1 Nov 2018 15:10:35 +0200
From: Eial Czerwacki <eial@...lemp.com>
To: Thomas Gleixner <tglx@...utronix.de>,
Randy Dunlap <rdunlap@...radead.org>
Cc: "Shai Fultheim (Shai@...leMP.com)" <Shai@...leMP.com>,
Andrew Morton <akpm@...ux-foundation.org>,
"broonie@...nel.org" <broonie@...nel.org>,
"mhocko@...e.cz" <mhocko@...e.cz>,
Stephen Rothwell <sfr@...b.auug.org.au>,
"linux-next@...r.kernel.org" <linux-next@...r.kernel.org>,
"linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>,
"linux-mm@...ck.org" <linux-mm@...ck.org>,
LKML <linux-kernel@...r.kernel.org>,
"mm-commits@...r.kernel.org" <mm-commits@...r.kernel.org>,
X86 ML <x86@...nel.org>, 'Oren Twaig' <oren@...lemp.com>
Subject: Re: [PATCH] x86/build: Build VSMP support only if selected
Greetings,
On 11/01/2018 12:39 PM, Shai Fultheim (Shai@...leMP.com) wrote:
> On 01/11/18 11:37, Thomas Gleixner wrote:
>
>> VSMP support is built even if CONFIG_X86_VSMP is not set. This leads to a build
>> breakage when CONFIG_PCI is disabled as well.
>>
>> Build VSMP code only when selected.
>
> This patch disables detect_vsmp_box() on systems without CONFIG_X86_VSMP, due to
> the recent 6da63eb241a05b0e676d68975e793c0521387141. This is significant
> regression that will affect significant number of deployments.
>
> We will reply shortly with an updated patch that fix the dependency on pv_irq_ops,
> and revert to CONFIG_PARAVIRT, with proper protection for CONFIG_PCI.
>
here is the proper patch which fixes the issue on hand:
>From ebff534f8cfa55d7c3ab798c44abe879f3fbe2b8 Mon Sep 17 00:00:00 2001
From: Eial Czerwacki <eial@...lemp.com>
Date: Thu, 1 Nov 2018 15:08:32 +0200
Subject: [PATCH] x86/build: Build VSMP support only if CONFIG_PCI is
selected
vsmp dependency of pv_irq_ops removed some years ago, so now let's clean
it up from vsmp_64.c.
In short, "cap & ctl & (1 << 4)" was always returning 0, as such we can
remove all the PARAVIRT/PARAVIRT_XXL code handling that.
However, the rest of the code depends on CONFIG_PCI, so fix it accordingly.
Signed-off-by: Eial Czerwacki <eial@...lemp.com>
Acked-by: Shai Fultheim <shai@...lemp.com>
---
arch/x86/Kconfig | 1 -
arch/x86/kernel/vsmp_64.c | 80
+++--------------------------------------------
2 files changed, 5 insertions(+), 76 deletions(-)
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index c51c989..4b187ca 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -524,7 +524,6 @@ config X86_VSMP
bool "ScaleMP vSMP"
select HYPERVISOR_GUEST
select PARAVIRT
- select PARAVIRT_XXL
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 1eae5af..c6d2b76 100644
--- a/arch/x86/kernel/vsmp_64.c
+++ b/arch/x86/kernel/vsmp_64.c
@@ -26,64 +26,7 @@
#define TOPOLOGY_REGISTER_OFFSET 0x10
-#if defined CONFIG_PCI && defined CONFIG_PARAVIRT_XXL
-/*
- * 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, void *ibuf,
- unsigned long addr, unsigned len)
-{
- switch (type) {
- case PARAVIRT_PATCH(irq.irq_enable):
- case PARAVIRT_PATCH(irq.irq_disable):
- case PARAVIRT_PATCH(irq.save_fl):
- case PARAVIRT_PATCH(irq.restore_fl):
- return paravirt_patch_default(type, ibuf, addr, len);
- default:
- return native_patch(type, ibuf, addr, len);
- }
-
-}
-
+#if defined CONFIG_PCI
static void __init set_vsmp_pv_ops(void)
{
void __iomem *address;
@@ -109,28 +52,12 @@ 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_ops.irq.irq_disable = PV_CALLEE_SAVE(vsmp_irq_disable);
- pv_ops.irq.irq_enable = PV_CALLEE_SAVE(vsmp_irq_enable);
- pv_ops.irq.save_fl = PV_CALLEE_SAVE(vsmp_save_fl);
- pv_ops.irq.restore_fl = PV_CALLEE_SAVE(vsmp_restore_fl);
- pv_ops.init.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);
early_iounmap(address, 8);
}
-#else
-static void __init set_vsmp_pv_ops(void)
-{
-}
-#endif
-
-#ifdef CONFIG_PCI
static int is_vsmp = -1;
static void __init detect_vsmp_box(void)
@@ -164,11 +91,14 @@ static int is_vsmp_box(void)
{
return 0;
}
+static void __init set_vsmp_pv_ops(void)
+{
+}
#endif
static void __init vsmp_cap_cpus(void)
{
-#if !defined(CONFIG_X86_VSMP) && defined(CONFIG_SMP)
+#if !defined(CONFIG_X86_VSMP) && defined(CONFIG_SMP) && defined(CONFIG_PCI)
void __iomem *address;
unsigned int cfg, topology, node_shift, maxcpus;
--
2.7.4
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