From 828554136bbacae6e39fc31b9cd7e7c660ad7530 Mon Sep 17 00:00:00 2001 From: Joerg Roedel Date: Thu, 1 Jul 2010 16:00:11 +0200 Subject: [PATCH] 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 Signed-off-by: Marcelo Tosatti --- arch/ia64/include/asm/kvm_host.h | 1 + arch/powerpc/include/asm/kvm_host.h | 1 + arch/s390/include/asm/kvm_host.h | 3 ++- arch/x86/include/asm/kvm_host.h | 3 ++- arch/x86/kvm/mmu.c | 8 ++++---- virt/kvm/kvm_main.c | 10 +++++----- 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; /*