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@xxxxxxx>
---
arch/powerpc/include/asm/kvm_host.h | 1 +
arch/powerpc/include/asm/kvm_ppc.h | 2 +
arch/powerpc/kvm/book3s_64_mmu_hv.c | 18 ++++++++++++++-
arch/powerpc/kvm/book3s_hv_builtin.c | 39 +++++++++++++++++++++++++++++++++-
4 files changed, 58 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h
index 8221e71..1843d5d 100644
--- a/arch/powerpc/include/asm/kvm_host.h
+++ b/arch/powerpc/include/asm/kvm_host.h
@@ -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 */
};
diff --git a/arch/powerpc/include/asm/kvm_ppc.h b/arch/powerpc/include/asm/kvm_ppc.h
index 1c37a2f..9d6dee0 100644
--- a/arch/powerpc/include/asm/kvm_ppc.h
+++ b/arch/powerpc/include/asm/kvm_ppc.h
@@ -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,
diff --git a/arch/powerpc/kvm/book3s_64_mmu_hv.c b/arch/powerpc/kvm/book3s_64_mmu_hv.c
index 783cd35..b3207c7 100644
--- a/arch/powerpc/kvm/book3s_64_mmu_hv.c
+++ b/arch/powerpc/kvm/book3s_64_mmu_hv.c
@@ -44,10 +44,23 @@ 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 */
+
+ /* using preallocated memory */
+ li = kvm_alloc_hpt();
+ if (li) {
+ hpt = (ulong)li->base_virt;
+ kvm->arch.hpt_li = li;
+ goto has_hpt;
+ }
+
+ /* using dynamic memory */
hpt = __get_free_pages(GFP_KERNEL|__GFP_ZERO|__GFP_REPEAT|__GFP_NOWARN,
HPT_ORDER - PAGE_SHIFT);
+
+has_hpt:
if (!hpt) {
pr_err("kvm_alloc_hpt: Couldn't alloc HPT\n");
return -ENOMEM;
@@ -88,7 +101,10 @@ 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 */
diff --git a/arch/powerpc/kvm/book3s_hv_builtin.c b/arch/powerpc/kvm/book3s_hv_builtin.c
index 7caed1d..bed1279 100644
--- a/arch/powerpc/kvm/book3s_hv_builtin.c
+++ b/arch/powerpc/kvm/book3s_hv_builtin.c
@@ -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) ||
--
1.6.0.2
--
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