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KVM: Allocate userspace memory for older userspace 

Allocate a userspace buffer for older userspaces.  Also eliminate phys_mem
buffer.  The memset() in kvmctl really kills initial memory usage but swapping
works even with old userspaces.

A side effect is that maximum guest side is reduced for older userspace on
i386.

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
This commit is contained in:
Anthony Liguori 2007-10-18 09:59:34 -05:00 committed by Avi Kivity
parent e56a7a28e2
commit 8d4e1288eb
2 changed files with 29 additions and 54 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
drivers/kvm/kvm.h
View File

@ -406,10 +406,8 @@ struct kvm_memory_slot {
gfn_t base_gfn;
unsigned long npages;
unsigned long flags;
struct page **phys_mem;
unsigned long *rmap;
unsigned long *dirty_bitmap;
int user_alloc; /* user allocated memory */
unsigned long userspace_addr;
};

81
drivers/kvm/kvm_main.c
View File

@ -42,6 +42,7 @@
#include <linux/profile.h>
#include <linux/kvm_para.h>
#include <linux/pagemap.h>
#include <linux/mman.h>
#include <asm/processor.h>
#include <asm/msr.h>
@ -300,36 +301,21 @@ static struct kvm *kvm_create_vm(void)
return kvm;
}
static void kvm_free_kernel_physmem(struct kvm_memory_slot *free)
{
int i;
for (i = 0; i < free->npages; ++i)
if (free->phys_mem[i])
__free_page(free->phys_mem[i]);
}
/*
* Free any memory in @free but not in @dont.
*/
static void kvm_free_physmem_slot(struct kvm_memory_slot *free,
struct kvm_memory_slot *dont)
{
if (!dont || free->phys_mem != dont->phys_mem)
if (free->phys_mem) {
if (!free->user_alloc)
kvm_free_kernel_physmem(free);
vfree(free->phys_mem);
}
if (!dont || free->rmap != dont->rmap)
vfree(free->rmap);
if (!dont || free->dirty_bitmap != dont->dirty_bitmap)
vfree(free->dirty_bitmap);
free->phys_mem = NULL;
free->npages = 0;
free->dirty_bitmap = NULL;
free->rmap = NULL;
}
static void kvm_free_physmem(struct kvm *kvm)
@ -712,10 +698,6 @@ static int kvm_vm_ioctl_set_memory_region(struct kvm *kvm,
goto out_unlock;
}
/* Deallocate if slot is being removed */
if (!npages)
new.phys_mem = NULL;
/* Free page dirty bitmap if unneeded */
if (!(new.flags & KVM_MEM_LOG_DIRTY_PAGES))
new.dirty_bitmap = NULL;
@ -723,29 +705,27 @@ static int kvm_vm_ioctl_set_memory_region(struct kvm *kvm,
r = -ENOMEM;
/* Allocate if a slot is being created */
if (npages && !new.phys_mem) {
new.phys_mem = vmalloc(npages * sizeof(struct page *));
if (!new.phys_mem)
goto out_unlock;
if (npages && !new.rmap) {
new.rmap = vmalloc(npages * sizeof(struct page *));
if (!new.rmap)
goto out_unlock;
memset(new.phys_mem, 0, npages * sizeof(struct page *));
memset(new.rmap, 0, npages * sizeof(*new.rmap));
if (user_alloc) {
new.user_alloc = 1;
if (user_alloc)
new.userspace_addr = mem->userspace_addr;
} else {
for (i = 0; i < npages; ++i) {
new.phys_mem[i] = alloc_page(GFP_HIGHUSER
| __GFP_ZERO);
if (!new.phys_mem[i])
goto out_unlock;
}
else {
down_write(&current->mm->mmap_sem);
new.userspace_addr = do_mmap(NULL, 0,
npages * PAGE_SIZE,
PROT_READ | PROT_WRITE,
MAP_SHARED | MAP_ANONYMOUS,
0);
up_write(&current->mm->mmap_sem);
if (IS_ERR((void *)new.userspace_addr))
goto out_unlock;
}
}
@ -1010,6 +990,8 @@ struct kvm_memory_slot *gfn_to_memslot(struct kvm *kvm, gfn_t gfn)
struct page *gfn_to_page(struct kvm *kvm, gfn_t gfn)
{
struct kvm_memory_slot *slot;
struct page *page[1];
int npages;
gfn = unalias_gfn(kvm, gfn);
slot = __gfn_to_memslot(kvm, gfn);
@ -1017,24 +999,19 @@ struct page *gfn_to_page(struct kvm *kvm, gfn_t gfn)
get_page(bad_page);
return bad_page;
}
if (slot->user_alloc) {
struct page *page[1];
int npages;
down_read(&current->mm->mmap_sem);
npages = get_user_pages(current, current->mm,
slot->userspace_addr
+ (gfn - slot->base_gfn) * PAGE_SIZE, 1,
1, 1, page, NULL);
up_read(&current->mm->mmap_sem);
if (npages != 1) {
get_page(bad_page);
return bad_page;
}
return page[0];
down_read(&current->mm->mmap_sem);
npages = get_user_pages(current, current->mm,
slot->userspace_addr
+ (gfn - slot->base_gfn) * PAGE_SIZE, 1,
1, 1, page, NULL);
up_read(&current->mm->mmap_sem);
if (npages != 1) {
get_page(bad_page);
return bad_page;
}
get_page(slot->phys_mem[gfn - slot->base_gfn]);
return slot->phys_mem[gfn - slot->base_gfn];
return page[0];
}
EXPORT_SYMBOL_GPL(gfn_to_page);