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KVM: Remove unnecessary divide operations 

This patch converts unnecessary divide and modulo operations
in the KVM large page related code into logical operations.
This allows to convert gfn_t to u64 while not breaking 32
bit builds.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
This commit is contained in:
Joerg Roedel 2010-07-01 16:00:11 +02:00 committed by Avi Kivity
parent 95c87e2b44
commit 828554136b
6 changed files with 15 additions and 11 deletions
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1
arch/ia64/include/asm/kvm_host.h
View File

@ -235,6 +235,7 @@ struct kvm_vm_data {
#define KVM_REQ_PTC_G 32
#define KVM_REQ_RESUME 33
#define KVM_HPAGE_GFN_SHIFT(x) 0
#define KVM_NR_PAGE_SIZES 1
#define KVM_PAGES_PER_HPAGE(x) 1

1
arch/powerpc/include/asm/kvm_host.h
View File

@ -35,6 +35,7 @@
#define KVM_COALESCED_MMIO_PAGE_OFFSET 1
/* We don't currently support large pages. */
#define KVM_HPAGE_GFN_SHIFT(x) 0
#define KVM_NR_PAGE_SIZES 1
#define KVM_PAGES_PER_HPAGE(x) (1UL<<31)

3
arch/s390/include/asm/kvm_host.h
View File

@ -41,7 +41,8 @@ struct sca_block {
} __attribute__((packed));
#define KVM_NR_PAGE_SIZES 2
#define KVM_HPAGE_SHIFT(x) (PAGE_SHIFT + ((x) - 1) * 8)
#define KVM_HPAGE_GFN_SHIFT(x) (((x) - 1) * 8)
#define KVM_HPAGE_SHIFT(x) (PAGE_SHIFT + KVM_HPAGE_GFN_SHIFT(x))
#define KVM_HPAGE_SIZE(x) (1UL << KVM_HPAGE_SHIFT(x))
#define KVM_HPAGE_MASK(x) (~(KVM_HPAGE_SIZE(x) - 1))
#define KVM_PAGES_PER_HPAGE(x) (KVM_HPAGE_SIZE(x) / PAGE_SIZE)

3
arch/x86/include/asm/kvm_host.h
View File

@ -44,7 +44,8 @@
/* KVM Hugepage definitions for x86 */
#define KVM_NR_PAGE_SIZES 3
#define KVM_HPAGE_SHIFT(x) (PAGE_SHIFT + (((x) - 1) * 9))
#define KVM_HPAGE_GFN_SHIFT(x) (((x) - 1) * 9)
#define KVM_HPAGE_SHIFT(x) (PAGE_SHIFT + KVM_HPAGE_GFN_SHIFT(x))
#define KVM_HPAGE_SIZE(x) (1UL << KVM_HPAGE_SHIFT(x))
#define KVM_HPAGE_MASK(x) (~(KVM_HPAGE_SIZE(x) - 1))
#define KVM_PAGES_PER_HPAGE(x) (KVM_HPAGE_SIZE(x) / PAGE_SIZE)

8
arch/x86/kvm/mmu.c
View File

@ -423,8 +423,8 @@ static int *slot_largepage_idx(gfn_t gfn,
{
unsigned long idx;
idx = (gfn / KVM_PAGES_PER_HPAGE(level)) -
(slot->base_gfn / KVM_PAGES_PER_HPAGE(level));
idx = (gfn >> KVM_HPAGE_GFN_SHIFT(level)) -
(slot->base_gfn >> KVM_HPAGE_GFN_SHIFT(level));
return &slot->lpage_info[level - 2][idx].write_count;
}
@ -528,8 +528,8 @@ static unsigned long *gfn_to_rmap(struct kvm *kvm, gfn_t gfn, int level)
if (likely(level == PT_PAGE_TABLE_LEVEL))
return &slot->rmap[gfn - slot->base_gfn];
idx = (gfn / KVM_PAGES_PER_HPAGE(level)) -
(slot->base_gfn / KVM_PAGES_PER_HPAGE(level));
idx = (gfn >> KVM_HPAGE_GFN_SHIFT(level)) -
(slot->base_gfn >> KVM_HPAGE_GFN_SHIFT(level));
return &slot->lpage_info[level - 2][idx].rmap_pde;
}

10
virt/kvm/kvm_main.c
View File

@ -626,9 +626,9 @@ int __kvm_set_memory_region(struct kvm *kvm,
if (new.lpage_info[i])
continue;
lpages = 1 + (base_gfn + npages - 1) /
KVM_PAGES_PER_HPAGE(level);
lpages -= base_gfn / KVM_PAGES_PER_HPAGE(level);
lpages = 1 + ((base_gfn + npages - 1)
>> KVM_HPAGE_GFN_SHIFT(level));
lpages -= base_gfn >> KVM_HPAGE_GFN_SHIFT(level);
new.lpage_info[i] = vmalloc(lpages * sizeof(*new.lpage_info[i]));
@ -638,9 +638,9 @@ int __kvm_set_memory_region(struct kvm *kvm,
memset(new.lpage_info[i], 0,
lpages * sizeof(*new.lpage_info[i]));
if (base_gfn % KVM_PAGES_PER_HPAGE(level))
if (base_gfn & (KVM_PAGES_PER_HPAGE(level) - 1))
new.lpage_info[i][0].write_count = 1;
if ((base_gfn+npages) % KVM_PAGES_PER_HPAGE(level))
if ((base_gfn+npages) & (KVM_PAGES_PER_HPAGE(level) - 1))
new.lpage_info[i][lpages - 1].write_count = 1;
ugfn = new.userspace_addr >> PAGE_SHIFT;
/*