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Commit d2a1b483 authored by Alexander Graf's avatar Alexander Graf Committed by Avi Kivity
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KVM: PPC: Add HPT preallocator 



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: default avatarAlexander Graf <agraf@suse.de>
Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
parent b7f5d011

arch/powerpc/include/asm/kvm_host.h

+1 −0
Original line number Diff line number Diff line
@@ -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 */

};

arch/powerpc/include/asm/kvm_ppc.h

+2 −0
Original line number Diff line number Diff line
@@ -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,

arch/powerpc/kvm/book3s_64_mmu_hv.c

+16 −3
Original line number Diff line number Diff line
@@ -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;
@@ -88,6 +98,9 @@ void kvmppc_free_hpt(struct kvm *kvm) 
{

	clear_bit(kvm->arch.lpid, lpid_inuse);

	vfree(kvm->arch.revmap);

	if (kvm->arch.hpt_li)

		kvm_release_hpt(kvm->arch.hpt_li);

	else

		free_pages(kvm->arch.hpt_virt, HPT_ORDER - PAGE_SHIFT);

}

arch/powerpc/kvm/book3s_hv_builtin.c

+38 −1
Original line number Diff line number Diff line
@@ -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) ||