[PATCH 29/52] KVM: PPC: Keep page physical addresses in per-slot arrays

Alexander Graf
2012-01-13T14:58:41Z

From: Paul Mackerras <paulus@samba.org>

This allocates an array for each memory slot that is added to store
the physical addresses of the pages in the slot. This array is
vmalloc'd and accessed in kvmppc_h_enter using real_vmalloc_addr().
This allows us to remove the ram_pginfo field from the kvm_arch
struct, and removes the 64GB guest RAM limit that we had.

We use the low-order bits of the array entries to store a flag
indicating that we have done get_page on the corresponding page,
and therefore need to call put_page when we are finished with the
page. Currently this is set for all pages except those in our
special RMO regions.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Alexander Graf <agraf@suse.de>
---
arch/powerpc/include/asm/kvm_host.h | 9 ++-
arch/powerpc/kvm/book3s_64_mmu_hv.c | 18 +++---
arch/powerpc/kvm/book3s_hv.c | 114 +++++++++++++++++------------------
arch/powerpc/kvm/book3s_hv_rm_mmu.c | 41 +++++++++++-
4 files changed, 107 insertions(+), 75 deletions(-)

diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h
index 629df2e..7a17ab5 100644
--- a/arch/powerpc/include/asm/kvm_host.h
+++ b/arch/powerpc/include/asm/kvm_host.h
@@ -38,6 +38,7 @@
#define KVM_MEMORY_SLOTS 32
/* memory slots that does not exposed to userspace */
#define KVM_PRIVATE_MEM_SLOTS 4
+#define KVM_MEM_SLOTS_NUM (KVM_MEMORY_SLOTS + KVM_PRIVATE_MEM_SLOTS)

#ifdef CONFIG_KVM_MMIO
#define KVM_COALESCED_MMIO_PAGE_OFFSET 1
@@ -175,25 +176,27 @@ struct revmap_entry {
unsigned long guest_rpte;
};

+/* Low-order bits in kvm->arch.slot_phys[][] */
+#define KVMPPC_GOT_PAGE 0x80
+
struct kvm_arch {
#ifdef CONFIG_KVM_BOOK3S_64_HV
unsigned long hpt_virt;
struct revmap_entry *revmap;
- unsigned long ram_npages;
unsigned long ram_psize;
unsigned long ram_porder;
- struct kvmppc_pginfo *ram_pginfo;
unsigned int lpid;
unsigned int host_lpid;
unsigned long host_lpcr;
unsigned long sdr1;
unsigned long host_sdr1;
int tlbie_lock;
- int n_rma_pages;
unsigned long lpcr;
unsigned long rmor;
struct kvmppc_rma_info *rma;
struct list_head spapr_tce_tables;
+ unsigned long *slot_phys[KVM_MEM_SLOTS_NUM];
+ int slot_npages[KVM_MEM_SLOTS_NUM];
unsigned short last_vcpu[NR_CPUS];
struct kvmppc_vcore *vcores[KVM_MAX_VCORES];
#endif /* CONFIG_KVM_BOOK3S_64_HV */
diff --git a/arch/powerpc/kvm/book3s_64_mmu_hv.c b/arch/powerpc/kvm/book3s_64_mmu_hv.c
index 80ece8d..e4c6069 100644
--- a/arch/powerpc/kvm/book3s_64_mmu_hv.c
+++ b/arch/powerpc/kvm/book3s_64_mmu_hv.c
@@ -98,16 +98,16 @@ void kvmppc_free_hpt(struct kvm *kvm)
void kvmppc_map_vrma(struct kvm *kvm, struct kvm_userspace_memory_region *mem)
{
unsigned long i;
- unsigned long npages = kvm->arch.ram_npages;
- unsigned long pfn;
+ unsigned long npages;
+ unsigned long pa;
unsigned long *hpte;
unsigned long hash;
unsigned long porder = kvm->arch.ram_porder;
struct revmap_entry *rev;
- struct kvmppc_pginfo *pginfo = kvm->arch.ram_pginfo;
+ unsigned long *physp;

- if (!pginfo)
- return;
+ physp = kvm->arch.slot_phys[mem->slot];
+ npages = kvm->arch.slot_npages[mem->slot];

/* VRMA can't be > 1TB */
if (npages > 1ul << (40 - porder))
@@ -117,9 +117,10 @@ void kvmppc_map_vrma(struct kvm *kvm, struct kvm_userspace_memory_region *mem)
npages = HPT_NPTEG;

for (i = 0; i < npages; ++i) {
- pfn = pginfo[i].pfn;
- if (!pfn)
+ pa = physp[i];
+ if (!pa)
break;
+ pa &= PAGE_MASK;
/* can't use hpt_hash since va > 64 bits */
hash = (i ^ (VRMA_VSID ^ (VRMA_VSID << 25))) & HPT_HASH_MASK;
/*
@@ -131,8 +132,7 @@ void kvmppc_map_vrma(struct kvm *kvm, struct kvm_userspace_memory_region *mem)
hash = (hash << 3) + 7;
hpte = (unsigned long *) (kvm->arch.hpt_virt + (hash << 4));
/* HPTE low word - RPN, protection, etc. */
- hpte[1] = (pfn << PAGE_SHIFT) | HPTE_R_R | HPTE_R_C |
- HPTE_R_M | PP_RWXX;
+ hpte[1] = pa | HPTE_R_R | HPTE_R_C | HPTE_R_M | PP_RWXX;
smp_wmb();
hpte[0] = HPTE_V_1TB_SEG | (VRMA_VSID << (40 - 16)) |
(i << (VRMA_PAGE_ORDER - 16)) | HPTE_V_BOLTED |
diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index b1e3b9c..a84fedc 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -50,14 +50,6 @@
#include <linux/vmalloc.h>
#include <linux/highmem.h>

-/*
- * For now, limit memory to 64GB and require it to be large pages.
- * This value is chosen because it makes the ram_pginfo array be
- * 64kB in size, which is about as large as we want to be trying
- * to allocate with kmalloc.
- */
-#define MAX_MEM_ORDER 36
-
#define LARGE_PAGE_ORDER 24 /* 16MB pages */

/* #define EXIT_DEBUG */
@@ -147,10 +139,12 @@ static unsigned long do_h_register_vpa(struct kvm_vcpu *vcpu,
unsigned long vcpuid, unsigned long vpa)
{
struct kvm *kvm = vcpu->kvm;
- unsigned long pg_index, ra, len;
+ unsigned long gfn, pg_index, ra, len;
unsigned long pg_offset;
void *va;
struct kvm_vcpu *tvcpu;
+ struct kvm_memory_slot *memslot;
+ unsigned long *physp;

tvcpu = kvmppc_find_vcpu(kvm, vcpuid);
if (!tvcpu)
@@ -164,14 +158,20 @@ static unsigned long do_h_register_vpa(struct kvm_vcpu *vcpu,
if (vpa & 0x7f)
return H_PARAMETER;
/* registering new area; convert logical addr to real */
- pg_index = vpa >> kvm->arch.ram_porder;
- pg_offset = vpa & (kvm->arch.ram_psize - 1);
- if (pg_index >= kvm->arch.ram_npages)
+ gfn = vpa >> PAGE_SHIFT;
+ memslot = gfn_to_memslot(kvm, gfn);
+ if (!memslot || !(memslot->flags & KVM_MEMSLOT_INVALID))
+ return H_PARAMETER;
+ physp = kvm->arch.slot_phys[memslot->id];
+ if (!physp)
return H_PARAMETER;
- if (kvm->arch.ram_pginfo[pg_index].pfn == 0)
+ pg_index = (gfn - memslot->base_gfn) >>
+ (kvm->arch.ram_porder - PAGE_SHIFT);
+ pg_offset = vpa & (kvm->arch.ram_psize - 1);
+ ra = physp[pg_index];
+ if (!ra)
return H_PARAMETER;
- ra = kvm->arch.ram_pginfo[pg_index].pfn << PAGE_SHIFT;
- ra |= pg_offset;
+ ra = (ra & PAGE_MASK) | pg_offset;
va = __va(ra);
if (flags <= 1)
len = *(unsigned short *)(va + 4);
@@ -1075,12 +1075,11 @@ int kvmppc_core_prepare_memory_region(struct kvm *kvm,
struct kvm_userspace_memory_region *mem)
{
unsigned long psize, porder;
- unsigned long i, npages, totalpages;
- unsigned long pg_ix;
- struct kvmppc_pginfo *pginfo;
+ unsigned long i, npages;
unsigned long hva;
struct kvmppc_rma_info *ri = NULL;
struct page *page;
+ unsigned long *phys;

/* For now, only allow 16MB pages */
porder = LARGE_PAGE_ORDER;
@@ -1092,20 +1091,21 @@ int kvmppc_core_prepare_memory_region(struct kvm *kvm,
return -EINVAL;
}

+ /* Allocate a slot_phys array */
npages = mem->memory_size >> porder;
- totalpages = (mem->guest_phys_addr + mem->memory_size) >> porder;
-
- /* More memory than we have space to track? */
- if (totalpages > (1ul << (MAX_MEM_ORDER - LARGE_PAGE_ORDER)))
- return -EINVAL;
+ phys = kvm->arch.slot_phys[mem->slot];
+ if (!phys) {
+ phys = vzalloc(npages * sizeof(unsigned long));
+ if (!phys)
+ return -ENOMEM;
+ kvm->arch.slot_phys[mem->slot] = phys;
+ kvm->arch.slot_npages[mem->slot] = npages;
+ }

/* Do we already have an RMA registered? */
if (mem->guest_phys_addr == 0 && kvm->arch.rma)
return -EINVAL;

- if (totalpages > kvm->arch.ram_npages)
- kvm->arch.ram_npages = totalpages;
-
/* Is this one of our preallocated RMAs? */
if (mem->guest_phys_addr == 0) {
struct vm_area_struct *vma;
@@ -1138,7 +1138,6 @@ int kvmppc_core_prepare_memory_region(struct kvm *kvm,
}
atomic_inc(&ri->use_count);
kvm->arch.rma = ri;
- kvm->arch.n_rma_pages = rma_size >> porder;

/* Update LPCR and RMOR */
lpcr = kvm->arch.lpcr;
@@ -1162,12 +1161,9 @@ int kvmppc_core_prepare_memory_region(struct kvm *kvm,
ri->base_pfn << PAGE_SHIFT, rma_size, lpcr);
}

- pg_ix = mem->guest_phys_addr >> porder;
- pginfo = kvm->arch.ram_pginfo + pg_ix;
- for (i = 0; i < npages; ++i, ++pg_ix) {
- if (ri && pg_ix < kvm->arch.n_rma_pages) {
- pginfo[i].pfn = ri->base_pfn +
- (pg_ix << (porder - PAGE_SHIFT));
+ for (i = 0; i < npages; ++i) {
+ if (ri && i < ri->npages) {
+ phys[i] = (ri->base_pfn << PAGE_SHIFT) + (i << porder);
continue;
}
hva = mem->userspace_addr + (i << porder);
@@ -1183,7 +1179,7 @@ int kvmppc_core_prepare_memory_region(struct kvm *kvm,
hva, compound_order(page));
goto err;
}
- pginfo[i].pfn = page_to_pfn(page);
+ phys[i] = (page_to_pfn(page) << PAGE_SHIFT) | KVMPPC_GOT_PAGE;
}

return 0;
@@ -1192,6 +1188,28 @@ int kvmppc_core_prepare_memory_region(struct kvm *kvm,
return -EINVAL;
}

+static void unpin_slot(struct kvm *kvm, int slot_id)
+{
+ unsigned long *physp;
+ unsigned long j, npages, pfn;
+ struct page *page;
+
+ physp = kvm->arch.slot_phys[slot_id];
+ npages = kvm->arch.slot_npages[slot_id];
+ if (physp) {
+ for (j = 0; j < npages; j++) {
+ if (!(physp[j] & KVMPPC_GOT_PAGE))
+ continue;
+ pfn = physp[j] >> PAGE_SHIFT;
+ page = pfn_to_page(pfn);
+ SetPageDirty(page);
+ put_page(page);
+ }
+ vfree(physp);
+ kvm->arch.slot_phys[slot_id] = NULL;
+ }
+}
+
void kvmppc_core_commit_memory_region(struct kvm *kvm,
struct kvm_userspace_memory_region *mem)
{
@@ -1203,8 +1221,6 @@ void kvmppc_core_commit_memory_region(struct kvm *kvm,
int kvmppc_core_init_vm(struct kvm *kvm)
{
long r;
- unsigned long npages = 1ul << (MAX_MEM_ORDER - LARGE_PAGE_ORDER);
- long err = -ENOMEM;
unsigned long lpcr;

/* Allocate hashed page table */
@@ -1214,19 +1230,9 @@ int kvmppc_core_init_vm(struct kvm *kvm)

INIT_LIST_HEAD(&kvm->arch.spapr_tce_tables);

- kvm->arch.ram_pginfo = kzalloc(npages * sizeof(struct kvmppc_pginfo),
- GFP_KERNEL);
- if (!kvm->arch.ram_pginfo) {
- pr_err("kvmppc_core_init_vm: couldn't alloc %lu bytes\n",
- npages * sizeof(struct kvmppc_pginfo));
- goto out_free;
- }
-
- kvm->arch.ram_npages = 0;
kvm->arch.ram_psize = 1ul << LARGE_PAGE_ORDER;
kvm->arch.ram_porder = LARGE_PAGE_ORDER;
kvm->arch.rma = NULL;
- kvm->arch.n_rma_pages = 0;

kvm->arch.host_sdr1 = mfspr(SPRN_SDR1);

@@ -1249,25 +1255,15 @@ int kvmppc_core_init_vm(struct kvm *kvm)
kvm->arch.lpcr = lpcr;

return 0;
-
- out_free:
- kvmppc_free_hpt(kvm);
- return err;
}

void kvmppc_core_destroy_vm(struct kvm *kvm)
{
- struct kvmppc_pginfo *pginfo;
unsigned long i;

- if (kvm->arch.ram_pginfo) {
- pginfo = kvm->arch.ram_pginfo;
- kvm->arch.ram_pginfo = NULL;
- for (i = kvm->arch.n_rma_pages; i < kvm->arch.ram_npages; ++i)
- if (pginfo[i].pfn)
- put_page(pfn_to_page(pginfo[i].pfn));
- kfree(pginfo);
- }
+ for (i = 0; i < KVM_MEM_SLOTS_NUM; i++)
+ unpin_slot(kvm, i);
+
if (kvm->arch.rma) {
kvm_release_rma(kvm->arch.rma);
kvm->arch.rma = NULL;
diff --git a/arch/powerpc/kvm/book3s_hv_rm_mmu.c b/arch/powerpc/kvm/book3s_hv_rm_mmu.c
index 6148493..84dae82 100644
--- a/arch/powerpc/kvm/book3s_hv_rm_mmu.c
+++ b/arch/powerpc/kvm/book3s_hv_rm_mmu.c
@@ -20,6 +20,25 @@
#include <asm/synch.h>
#include <asm/ppc-opcode.h>

+/*
+ * Since this file is built in even if KVM is a module, we need
+ * a local copy of this function for the case where kvm_main.c is
+ * modular.
+ */
+static struct kvm_memory_slot *builtin_gfn_to_memslot(struct kvm *kvm,
+ gfn_t gfn)
+{
+ struct kvm_memslots *slots;
+ struct kvm_memory_slot *memslot;
+
+ slots = kvm_memslots(kvm);
+ kvm_for_each_memslot(memslot, slots)
+ if (gfn >= memslot->base_gfn &&
+ gfn < memslot->base_gfn + memslot->npages)
+ return memslot;
+ return NULL;
+}
+
/* Translate address of a vmalloc'd thing to a linear map address */
static void *real_vmalloc_addr(void *x)
{
@@ -59,10 +78,12 @@ long kvmppc_h_enter(struct kvm_vcpu *vcpu, unsigned long flags,
{
unsigned long porder;
struct kvm *kvm = vcpu->kvm;
- unsigned long i, lpn, pa;
+ unsigned long i, gfn, lpn, pa;
unsigned long *hpte;
struct revmap_entry *rev;
unsigned long g_ptel = ptel;
+ struct kvm_memory_slot *memslot;
+ unsigned long *physp;

/* only handle 4k, 64k and 16M pages for now */
porder = 12;
@@ -80,12 +101,24 @@ long kvmppc_h_enter(struct kvm_vcpu *vcpu, unsigned long flags,
} else
return H_PARAMETER;
}
- lpn = (ptel & HPTE_R_RPN) >> kvm->arch.ram_porder;
- if (lpn >= kvm->arch.ram_npages || porder > kvm->arch.ram_porder)
+ if (porder > kvm->arch.ram_porder)
return H_PARAMETER;
- pa = kvm->arch.ram_pginfo[lpn].pfn << PAGE_SHIFT;
+
+ gfn = ((ptel & HPTE_R_RPN) & ~((1ul << porder) - 1)) >> PAGE_SHIFT;
+ memslot = builtin_gfn_to_memslot(kvm, gfn);
+ if (!(memslot && !(memslot->flags & KVM_MEMSLOT_INVALID)))
+ return H_PARAMETER;
+ physp = kvm->arch.slot_phys[memslot->id];
+ if (!physp)
+ return H_PARAMETER;
+
+ lpn = (gfn - memslot->base_gfn) >> (kvm->arch.ram_porder - PAGE_SHIFT);
+ physp = real_vmalloc_addr(physp + lpn);
+ pa = *physp;
if (!pa)
return H_PARAMETER;
+ pa &= PAGE_MASK;
+
/* Check WIMG */
if ((ptel & HPTE_R_WIMG) != HPTE_R_M &&
(ptel & HPTE_R_WIMG) != (HPTE_R_W | HPTE_R_I | HPTE_R_M))
--
1.6.0.2