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authorJoerg Roedel <joerg.roedel@amd.com>2010-07-01 16:00:11 +0200
committerAvi Kivity <avi@redhat.com>2010-08-01 10:47:30 +0300
commit828554136bbacae6e39fc31b9cd7e7c660ad7530 (patch)
tree4e2ec85ff33c9c1e7245e83ed8e4fa3791007ef7
parent95c87e2b4460a488ec7ce42f273893e410ab385a (diff)
downloadlwn-828554136bbacae6e39fc31b9cd7e7c660ad7530.tar.gz
lwn-828554136bbacae6e39fc31b9cd7e7c660ad7530.zip
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>
-rw-r--r--arch/ia64/include/asm/kvm_host.h1
-rw-r--r--arch/powerpc/include/asm/kvm_host.h1
-rw-r--r--arch/s390/include/asm/kvm_host.h3
-rw-r--r--arch/x86/include/asm/kvm_host.h3
-rw-r--r--arch/x86/kvm/mmu.c8
-rw-r--r--virt/kvm/kvm_main.c10
6 files changed, 15 insertions, 11 deletions
diff --git a/arch/ia64/include/asm/kvm_host.h b/arch/ia64/include/asm/kvm_host.h
index a362e67e0ca6..2f229e5de498 100644
--- a/arch/ia64/include/asm/kvm_host.h
+++ b/arch/ia64/include/asm/kvm_host.h
@@ -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
diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h
index e004eafcd3f0..b0b23c007d6e 100644
--- a/arch/powerpc/include/asm/kvm_host.h
+++ b/arch/powerpc/include/asm/kvm_host.h
@@ -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)
diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
index b95710a1f5dd..cef7dbf69dfc 100644
--- a/arch/s390/include/asm/kvm_host.h
+++ b/arch/s390/include/asm/kvm_host.h
@@ -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)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 2bda62485c4c..50c79b9f5c38 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -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)
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index ca07ed083b59..a20fd613acfe 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -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;
}
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index ec2e3c6ac7ed..a60b6b053b6f 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -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;
/*