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KVM: PPC: Add HPT preallocator

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We're currently allocating 16MB of linear memory on demand when creating
a guest. That does work some times, but finding 16MB of linear memory
available in the system at runtime is definitely not a given.

So let's add another command line option similar to the RMA preallocator,
that we can use to keep a pool of page tables around. Now, when a guest
gets created it has a pretty low chance of receiving an OOM.

Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Avi Kivity <avi@redhat.com>
This commit is contained in:
Alexander Graf 2012-01-16 19:12:11 +01:00 committed by Avi Kivity
parent b7f5d0114c
commit d2a1b483a4
4 changed files with 57 additions and 4 deletions
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1
arch/powerpc/include/asm/kvm_host.h
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@ -235,6 +235,7 @@ struct kvm_arch {
int slot_npages[KVM_MEM_SLOTS_NUM];
unsigned short last_vcpu[NR_CPUS];
struct kvmppc_vcore *vcores[KVM_MAX_VCORES];
struct kvmppc_linear_info *hpt_li;
#endif /* CONFIG_KVM_BOOK3S_64_HV */
};

2
arch/powerpc/include/asm/kvm_ppc.h
View File

@ -130,6 +130,8 @@ extern long kvm_vm_ioctl_allocate_rma(struct kvm *kvm,
struct kvm_allocate_rma *rma);
extern struct kvmppc_linear_info *kvm_alloc_rma(void);
extern void kvm_release_rma(struct kvmppc_linear_info *ri);
extern struct kvmppc_linear_info *kvm_alloc_hpt(void);
extern void kvm_release_hpt(struct kvmppc_linear_info *li);
extern int kvmppc_core_init_vm(struct kvm *kvm);
extern void kvmppc_core_destroy_vm(struct kvm *kvm);
extern int kvmppc_core_prepare_memory_region(struct kvm *kvm,

19
arch/powerpc/kvm/book3s_64_mmu_hv.c
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@ -44,10 +44,20 @@ long kvmppc_alloc_hpt(struct kvm *kvm)
unsigned long hpt;
unsigned long lpid;
struct revmap_entry *rev;
struct kvmppc_linear_info *li;
/* Allocate guest's hashed page table */
hpt = __get_free_pages(GFP_KERNEL|__GFP_ZERO|__GFP_REPEAT|__GFP_NOWARN,
HPT_ORDER - PAGE_SHIFT);
li = kvm_alloc_hpt();
if (li) {
/* using preallocated memory */
hpt = (ulong)li->base_virt;
kvm->arch.hpt_li = li;
} else {
/* using dynamic memory */
hpt = __get_free_pages(GFP_KERNEL|__GFP_ZERO|__GFP_REPEAT|
__GFP_NOWARN, HPT_ORDER - PAGE_SHIFT);
}
if (!hpt) {
pr_err("kvm_alloc_hpt: Couldn't alloc HPT\n");
return -ENOMEM;
@ -88,7 +98,10 @@ void kvmppc_free_hpt(struct kvm *kvm)
{
clear_bit(kvm->arch.lpid, lpid_inuse);
vfree(kvm->arch.revmap);
free_pages(kvm->arch.hpt_virt, HPT_ORDER - PAGE_SHIFT);
if (kvm->arch.hpt_li)
kvm_release_hpt(kvm->arch.hpt_li);
else
free_pages(kvm->arch.hpt_virt, HPT_ORDER - PAGE_SHIFT);
}
/* Bits in first HPTE dword for pagesize 4k, 64k or 16M */

39
arch/powerpc/kvm/book3s_hv_builtin.c
View File

@ -19,6 +19,7 @@
#include <asm/kvm_book3s.h>
#define KVM_LINEAR_RMA 0
#define KVM_LINEAR_HPT 1
static void __init kvm_linear_init_one(ulong size, int count, int type);
static struct kvmppc_linear_info *kvm_alloc_linear(int type);
@ -97,6 +98,39 @@ void kvm_release_rma(struct kvmppc_linear_info *ri)
}
EXPORT_SYMBOL_GPL(kvm_release_rma);
/*************** HPT *************/
/*
* This maintains a list of big linear HPT tables that contain the GVA->HPA
* memory mappings. If we don't reserve those early on, we might not be able
* to get a big (usually 16MB) linear memory region from the kernel anymore.
*/
static unsigned long kvm_hpt_count;
static int __init early_parse_hpt_count(char *p)
{
if (!p)
return 1;
kvm_hpt_count = simple_strtoul(p, NULL, 0);
return 0;
}
early_param("kvm_hpt_count", early_parse_hpt_count);
struct kvmppc_linear_info *kvm_alloc_hpt(void)
{
return kvm_alloc_linear(KVM_LINEAR_HPT);
}
EXPORT_SYMBOL_GPL(kvm_alloc_hpt);
void kvm_release_hpt(struct kvmppc_linear_info *li)
{
kvm_release_linear(li);
}
EXPORT_SYMBOL_GPL(kvm_release_hpt);
/*************** generic *************/
static LIST_HEAD(free_linears);
@ -114,7 +148,7 @@ static void __init kvm_linear_init_one(ulong size, int count, int type)
if (!count)
return;
typestr = (type == KVM_LINEAR_RMA) ? "RMA" : "";
typestr = (type == KVM_LINEAR_RMA) ? "RMA" : "HPT";
npages = size >> PAGE_SHIFT;
linear_info = alloc_bootmem(count * sizeof(struct kvmppc_linear_info));
@ -173,6 +207,9 @@ static void kvm_release_linear(struct kvmppc_linear_info *ri)
*/
void __init kvm_linear_init(void)
{
/* HPT */
kvm_linear_init_one(1 << HPT_ORDER, kvm_hpt_count, KVM_LINEAR_HPT);
/* RMA */
/* Only do this on PPC970 in HV mode */
if (!cpu_has_feature(CPU_FTR_HVMODE) ||