Izik Eidus wrote:
Anthony Liguori wrote:
I think it's just a matter of calling do_mmap() with the appropriate
parameters. It looks likes there's some drivers call do_mmap()
directly.
yea, i think you right, this is excellent idea!, when we will merge
the swapping to kvm, we will add swapping support to older userspace.
Here's a patch against your series. The memset in kvmctl ends up making
the guest use all physical memory to start off with but I did confirm
that once the system is under memory pressure, the guest's memory
becomes swappable. Of course, it's quite painful :-)
A nice thing though is that a lot of the code becomes a bit cleaner and
we can eliminate the phys_mem array entirely.
Regards,
Anthony Liguori
Subject: [PATCH] Allocate userspace memory for older userspace
From: Anthony Liguori <[EMAIL PROTECTED]>
Cc: Avi Kivity <[EMAIL PROTECTED]>
Cc: Izik Eidus <[EMAIL PROTECTED]>
Allocate a userspace buffer for older userspaces. Also eliminate phys_mem
buffer. The memset() in kvmctl really kills initial memory usage but swapping
does even with old userspaces.
Signed-off-by: Anthony Liguori <[EMAIL PROTECTED]>
diff --git a/drivers/kvm/kvm.h b/drivers/kvm/kvm.h
index 74b427f..c904ea3 100644
--- a/drivers/kvm/kvm.h
+++ b/drivers/kvm/kvm.h
@@ -405,10 +405,8 @@ 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;
};
diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
index f58d49b..aa5666f 100644
--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -41,6 +41,7 @@
#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>
@@ -319,34 +320,18 @@ 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;
}
@@ -731,10 +716,6 @@ 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;
@@ -742,29 +723,27 @@ 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 = 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(¤t->mm->mmap_sem);
+ new.userspace_addr = do_mmap(NULL, 0,
+ npages * PAGE_SIZE,
+ PROT_READ | PROT_WRITE,
+ MAP_SHARED | MAP_ANONYMOUS,
+ 0);
+ up_write(¤t->mm->mmap_sem);
+
+ if (new.userspace_addr > -1024UL)
+ goto out_unlock;
}
}
@@ -1029,6 +1008,8 @@ 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);
@@ -1036,24 +1017,19 @@ 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(¤t->mm->mmap_sem);
- npages = get_user_pages(current, current->mm,
- slot->userspace_addr
- + (gfn - slot->base_gfn) * PAGE_SIZE, 1,
- 1, 0, page, NULL);
- up_read(¤t->mm->mmap_sem);
- if (npages != 1) {
- get_page(bad_page);
- return bad_page;
- }
- return page[0];
+
+ down_read(¤t->mm->mmap_sem);
+ npages = get_user_pages(current, current->mm,
+ slot->userspace_addr
+ + (gfn - slot->base_gfn) * PAGE_SIZE, 1,
+ 1, 0, page, NULL);
+ up_read(¤t->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);
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