[RFC PATCH v1 2/2] xen_nopv: Combine a bunch of the PV features that can be disabled

[Konrad Rzeszutek Wilk]

under one parameter. Removes the xen_nopvspin parameter and
makes it part of the xen_nopv.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
---
 Documentation/kernel-parameters.txt | 15 +++++------
 arch/x86/xen/enlighten.c            | 50 +++++++++++++++++++++++++++++++++----
 arch/x86/xen/spinlock.c             | 18 ++++---------
 arch/x86/xen/xen-ops.h              |  4 +++
 4 files changed, 62 insertions(+), 25 deletions(-)

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 22a4b68..73cd745 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -4125,13 +4125,14 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 				the unplug protocol
 			never -- do not unplug even if version check succeeds
 
-	xen_nopvspin	[X86,XEN]
-			Disables the ticketlock slowpath using Xen PV
-			optimizations.
-
-	xen_nopv	[X86]
-			Disables the PV optimizations forcing the HVM guest to
-			run as generic HVM guest with no PV drivers.
+	xen_nopv=	[X86,XEN]
+			Disables various (or all) PV optimizations forcing the
+			HVM (or PV) guest to run without them.
+			Format: [off0,][off]
+			all -- every PV feature on HVM.
+			spin -- Disables the ticketlock slowpath using Xen PV
+                                optimizations (PV and HVM).
+			ipi - Disable PV event channel IPI (on HVM).
 
 	xirc2ps_cs=	[NET,PCMCIA]
 			Format:
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 30d12af..c644d2c 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -1829,17 +1829,57 @@ static void __init xen_hvm_guest_init(void)
 }
 #endif
 
-static bool xen_nopv = false;
+static unsigned int xen_nopv_feat;
+#define XEN_NOPV_SPIN	1<<1
+#define XEN_NOPV_IPI	1<<2
+#define XEN_NOPV_ALL	(XEN_NOPV_SPIN | XEN_NOPV_IPI)
+
+bool xen_no_pvspin(void)
+{
+	return xen_nopv_feat & XEN_NOPV_SPIN;
+}
+
+bool xen_no_pv(void)
+{
+	return xen_nopv_feat & XEN_NOPV_ALL;
+}
+
+bool xen_no_pvipi(void)
+{
+	return xen_nopv_feat & XEN_NOPV_IPI;
+}
+
 static __init int xen_parse_nopv(char *arg)
 {
-       xen_nopv = true;
-       return 0;
+	char *p, *q;
+	int l;
+
+	for (p = arg; p; p = q) {
+		q = strchr(p, ',');
+		if (q) {
+			l = q - p;
+			q++;
+		} else {
+			l = strlen(p);
+		}
+		if (!strncmp(p, "spin", l))
+			xen_nopv_feat |= XEN_NOPV_SPIN;
+		else if (!strncmp(p, "all", l))
+			xen_nopv_feat = XEN_NOPV_ALL;
+		else if (!strncmp(p, "ipi", l))
+			xen_nopv_feat |= XEN_NOPV_IPI;
+		else
+			printk(KERN_WARNING "unrecognised option '%s' "
+				 "in parameter 'xen_nopv'\n", p);
+	}
+	printk(KERN_DEBUG "xen_nopv_feat = 0x%x\n", xen_nopv_feat);
+	return 0;
 }
 early_param("xen_nopv", xen_parse_nopv);
 
 static uint32_t __init xen_platform(void)
 {
-	if (xen_nopv)
+	if (xen_no_pv())
 		return 0;
 
 	return xen_cpuid_base();
@@ -1847,7 +1887,7 @@ static uint32_t __init xen_platform(void)
 
 bool xen_hvm_need_lapic(void)
 {
-	if (xen_nopv)
+	if (xen_no_pv())
 		return false;
 	if (xen_pv_domain())
 		return false;
diff --git a/arch/x86/xen/spinlock.c b/arch/x86/xen/spinlock.c
index 9e2ba5c..31b91e9 100644
--- a/arch/x86/xen/spinlock.c
+++ b/arch/x86/xen/spinlock.c
@@ -19,7 +19,6 @@
 
 static DEFINE_PER_CPU(int, lock_kicker_irq) = -1;
 static DEFINE_PER_CPU(char *, irq_name);
-static bool xen_pvspin = true;
 
 #ifdef CONFIG_QUEUED_SPINLOCKS
 
@@ -277,7 +276,7 @@ void xen_init_lock_cpu(int cpu)
 	int irq;
 	char *name;
 
-	if (!xen_pvspin)
+	if (!xen_no_pvspin())
 		return;
 
 	WARN(per_cpu(lock_kicker_irq, cpu) >= 0, "spinlock on CPU%d exists on IRQ%d!\n",
@@ -302,7 +301,7 @@ void xen_init_lock_cpu(int cpu)
 
 void xen_uninit_lock_cpu(int cpu)
 {
-	if (!xen_pvspin)
+	if (!xen_no_pvspin())
 		return;
 
 	unbind_from_irqhandler(per_cpu(lock_kicker_irq, cpu), NULL);
@@ -323,7 +322,7 @@ void xen_uninit_lock_cpu(int cpu)
 void __init xen_init_spinlocks(void)
 {
 
-	if (!xen_pvspin) {
+	if (!xen_no_pvspin()) {
 		printk(KERN_DEBUG "xen: PV spinlocks disabled\n");
 		return;
 	}
@@ -348,7 +347,7 @@ void __init xen_init_spinlocks(void)
  */
 static __init int xen_init_spinlocks_jump(void)
 {
-	if (!xen_pvspin)
+	if (!xen_no_pvspin())
 		return 0;
 
 	if (!xen_domain())
@@ -359,13 +358,6 @@ static __init int xen_init_spinlocks_jump(void)
 }
 early_initcall(xen_init_spinlocks_jump);
 
-static __init int xen_parse_nopvspin(char *arg)
-{
-	xen_pvspin = false;
-	return 0;
-}
-early_param("xen_nopvspin", xen_parse_nopvspin);
-
 #if defined(CONFIG_XEN_DEBUG_FS) && !defined(CONFIG_QUEUED_SPINLOCKS)
 
 static struct dentry *d_spin_debug;
@@ -377,7 +369,7 @@ static int __init xen_spinlock_debugfs(void)
 	if (d_xen == NULL)
 		return -ENOMEM;
 
-	if (!xen_pvspin)
+	if (xen_no_pvspin())
 		return 0;
 
 	d_spin_debug = debugfs_create_dir("spinlocks", d_xen);
diff --git a/arch/x86/xen/xen-ops.h b/arch/x86/xen/xen-ops.h
index 1399423..3652d38 100644
--- a/arch/x86/xen/xen-ops.h
+++ b/arch/x86/xen/xen-ops.h
@@ -149,4 +149,8 @@ __visible void xen_adjust_exception_frame(void);
 extern int xen_panic_handler_init(void);
 
 void xen_pvh_secondary_vcpu_init(int cpu);
+
+bool xen_no_pvspin(void);
+bool xen_no_pvipi(void);
+bool xen_no_pv(void);
 #endif /* XEN_OPS_H */
-- 
2.4.3

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