Re: [PATCH 2/10] Trivial: Remove KVM_IRQ_BITMAP macro

[Rusty Russell <rusty-8n+1lVoiYb80n/F98K4Iww@public.gmane.org>]

On Tue, 2007-07-17 at 16:25 +0300, Avi Kivity wrote:
> Rusty Russell wrote:
> > Creating one's own BITMAP macro seems suboptimal: if we use manual
> > arithmetic in the one place exposed to userspace, we can use standard
> > macros elsewhere.
> >
> > The - 7 + 8 calc is overkill: can NR_IRQ_WORDS ever really change?
> >   
> 
> Looks like it can:

Sure, but the number 256 is part of the x86 architecture.  A paravirt
guest could choose to have more interrupts, but is there really a point?

> >  /* for KVM_CREATE_MEMORY_REGION */
> >  struct kvm_memory_region {
> > @@ -163,7 +157,7 @@ struct kvm_sregs {
> >  	__u64 cr0, cr2, cr3, cr4, cr8;
> >  	__u64 efer;
> >  	__u64 apic_base;
> > -	__u64 interrupt_bitmap[KVM_IRQ_BITMAP_SIZE(__u64)];
> > +	__u64 interrupt_bitmap[(KVM_NR_INTERRUPTS + 7) / 8];
> >  };
> >  
> >   
> 
> The size is in bytes, but the element type is __u64.

Doh, fixed here:
==
Use standard BITMAP macros, open-code userspace-exposed header.

Creating one's own BITMAP macro seems suboptimal: if we use manual
arithmetic in the one place exposed to userspace, we can use standard
macros elsewhere.

Signed-off-by: Rusty Russell <rusty-8n+1lVoiYb80n/F98K4Iww@public.gmane.org>

diff -r 85a8c51d3df8 drivers/kvm/kvm.h
--- a/drivers/kvm/kvm.h	Tue Jul 17 13:10:00 2007 +1000
+++ b/drivers/kvm/kvm.h	Tue Jul 17 13:15:22 2007 +1000
@@ -342,8 +342,7 @@ struct kvm_vcpu {
 	int guest_mode;
 	unsigned long requests;
 	unsigned long irq_summary; /* bit vector: 1 per word in irq_pending */
-#define NR_IRQ_WORDS KVM_IRQ_BITMAP_SIZE(unsigned long)
-	unsigned long irq_pending[NR_IRQ_WORDS];
+	DECLARE_BITMAP(irq_pending, KVM_NR_INTERRUPTS);
 	unsigned long regs[NR_VCPU_REGS]; /* for rsp: vcpu_load_rsp_rip() */
 	unsigned long rip;      /* needs vcpu_load_rsp_rip() */
 
diff -r 85a8c51d3df8 drivers/kvm/kvm_main.c
--- a/drivers/kvm/kvm_main.c	Tue Jul 17 13:10:00 2007 +1000
+++ b/drivers/kvm/kvm_main.c	Tue Jul 17 16:26:10 2007 +1000
@@ -2122,7 +2122,7 @@ static int kvm_vcpu_ioctl_set_sregs(stru
 	memcpy(vcpu->irq_pending, sregs->interrupt_bitmap,
 	       sizeof vcpu->irq_pending);
 	vcpu->irq_summary = 0;
-	for (i = 0; i < NR_IRQ_WORDS; ++i)
+	for (i = 0; i < ARRAY_SIZE(vcpu->irq_pending); ++i)
 		if (vcpu->irq_pending[i])
 			__set_bit(i, &vcpu->irq_summary);
 
diff -r 85a8c51d3df8 include/linux/kvm.h
--- a/include/linux/kvm.h	Tue Jul 17 13:10:00 2007 +1000
+++ b/include/linux/kvm.h	Tue Jul 17 13:25:48 2007 +1000
@@ -12,14 +12,8 @@
 
 #define KVM_API_VERSION 12
 
-/*
- * Architectural interrupt line count, and the size of the bitmap needed
- * to hold them.
- */
+/* Architectural interrupt line count. */
 #define KVM_NR_INTERRUPTS 256
-#define KVM_IRQ_BITMAP_SIZE_BYTES    ((KVM_NR_INTERRUPTS + 7) / 8)
-#define KVM_IRQ_BITMAP_SIZE(type)    (KVM_IRQ_BITMAP_SIZE_BYTES / sizeof(type))
-
 
 /* for KVM_CREATE_MEMORY_REGION */
 struct kvm_memory_region {
@@ -163,7 +157,7 @@ struct kvm_sregs {
 	__u64 cr0, cr2, cr3, cr4, cr8;
 	__u64 efer;
 	__u64 apic_base;
-	__u64 interrupt_bitmap[KVM_IRQ_BITMAP_SIZE(__u64)];
+	__u64 interrupt_bitmap[(KVM_NR_INTERRUPTS + 63) / 64];
 };
 
 struct kvm_msr_entry {



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