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KVM: PPC: Allow use of small pages to back Book3S HV guests
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This relaxes the requirement that the guest memory be provided as
16MB huge pages, allowing it to be provided as normal memory, i.e.
in pages of PAGE_SIZE bytes (4k or 64k).  To allow this, we index
the kvm->arch.slot_phys[] arrays with a small page index, even if
huge pages are being used, and use the low-order 5 bits of each
entry to store the order of the enclosing page with respect to
normal pages, i.e. log_2(enclosing_page_size / PAGE_SIZE).

Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Avi Kivity <avi@redhat.com>
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Paul Mackerras authored and Avi Kivity committed Mar 5, 2012
1 parent c77162d commit da9d1d7
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Showing 7 changed files with 132 additions and 69 deletions.
10 changes: 10 additions & 0 deletions arch/powerpc/include/asm/kvm_book3s_64.h
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Original file line number Diff line number Diff line change
Expand Up @@ -113,4 +113,14 @@ static inline unsigned long hpte_page_size(unsigned long h, unsigned long l)
return 0; /* error */
}

static inline bool slot_is_aligned(struct kvm_memory_slot *memslot,
unsigned long pagesize)
{
unsigned long mask = (pagesize >> PAGE_SHIFT) - 1;

if (pagesize <= PAGE_SIZE)
return 1;
return !(memslot->base_gfn & mask) && !(memslot->npages & mask);
}

#endif /* __ASM_KVM_BOOK3S_64_H__ */
3 changes: 1 addition & 2 deletions arch/powerpc/include/asm/kvm_host.h
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Original file line number Diff line number Diff line change
Expand Up @@ -177,14 +177,13 @@ struct revmap_entry {
};

/* Low-order bits in kvm->arch.slot_phys[][] */
#define KVMPPC_PAGE_ORDER_MASK 0x1f
#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_psize;
unsigned long ram_porder;
unsigned int lpid;
unsigned int host_lpid;
unsigned long host_lpcr;
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2 changes: 1 addition & 1 deletion arch/powerpc/include/asm/kvm_ppc.h
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Original file line number Diff line number Diff line change
Expand Up @@ -122,7 +122,7 @@ extern void kvmppc_free_hpt(struct kvm *kvm);
extern long kvmppc_prepare_vrma(struct kvm *kvm,
struct kvm_userspace_memory_region *mem);
extern void kvmppc_map_vrma(struct kvm_vcpu *vcpu,
struct kvm_memory_slot *memslot);
struct kvm_memory_slot *memslot, unsigned long porder);
extern int kvmppc_pseries_do_hcall(struct kvm_vcpu *vcpu);
extern long kvm_vm_ioctl_create_spapr_tce(struct kvm *kvm,
struct kvm_create_spapr_tce *args);
Expand Down
1 change: 1 addition & 0 deletions arch/powerpc/include/asm/reg.h
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Original file line number Diff line number Diff line change
Expand Up @@ -237,6 +237,7 @@
#define LPCR_ISL (1ul << (63-2))
#define LPCR_VC_SH (63-2)
#define LPCR_DPFD_SH (63-11)
#define LPCR_VRMASD (0x1ful << (63-16))
#define LPCR_VRMA_L (1ul << (63-12))
#define LPCR_VRMA_LP0 (1ul << (63-15))
#define LPCR_VRMA_LP1 (1ul << (63-16))
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122 changes: 83 additions & 39 deletions arch/powerpc/kvm/book3s_64_mmu_hv.c
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Original file line number Diff line number Diff line change
Expand Up @@ -34,8 +34,6 @@
#include <asm/ppc-opcode.h>
#include <asm/cputable.h>

/* Pages in the VRMA are 16MB pages */
#define VRMA_PAGE_ORDER 24
#define VRMA_VSID 0x1ffffffUL /* 1TB VSID reserved for VRMA */

/* POWER7 has 10-bit LPIDs, PPC970 has 6-bit LPIDs */
Expand Down Expand Up @@ -95,17 +93,31 @@ void kvmppc_free_hpt(struct kvm *kvm)
free_pages(kvm->arch.hpt_virt, HPT_ORDER - PAGE_SHIFT);
}

void kvmppc_map_vrma(struct kvm_vcpu *vcpu, struct kvm_memory_slot *memslot)
/* Bits in first HPTE dword for pagesize 4k, 64k or 16M */
static inline unsigned long hpte0_pgsize_encoding(unsigned long pgsize)
{
return (pgsize > 0x1000) ? HPTE_V_LARGE : 0;
}

/* Bits in second HPTE dword for pagesize 4k, 64k or 16M */
static inline unsigned long hpte1_pgsize_encoding(unsigned long pgsize)
{
return (pgsize == 0x10000) ? 0x1000 : 0;
}

void kvmppc_map_vrma(struct kvm_vcpu *vcpu, struct kvm_memory_slot *memslot,
unsigned long porder)
{
struct kvm *kvm = vcpu->kvm;
unsigned long i;
unsigned long npages;
unsigned long hp_v, hp_r;
unsigned long addr, hash;
unsigned long porder = kvm->arch.ram_porder;
unsigned long psize;
unsigned long hp0, hp1;
long ret;

npages = kvm->arch.slot_npages[memslot->id];
psize = 1ul << porder;
npages = memslot->npages >> (porder - PAGE_SHIFT);

/* VRMA can't be > 1TB */
if (npages > 1ul << (40 - porder))
Expand All @@ -114,6 +126,11 @@ void kvmppc_map_vrma(struct kvm_vcpu *vcpu, struct kvm_memory_slot *memslot)
if (npages > HPT_NPTEG)
npages = HPT_NPTEG;

hp0 = HPTE_V_1TB_SEG | (VRMA_VSID << (40 - 16)) |
HPTE_V_BOLTED | hpte0_pgsize_encoding(psize);
hp1 = hpte1_pgsize_encoding(psize) |
HPTE_R_R | HPTE_R_C | HPTE_R_M | PP_RWXX;

for (i = 0; i < npages; ++i) {
addr = i << porder;
/* can't use hpt_hash since va > 64 bits */
Expand All @@ -125,10 +142,8 @@ void kvmppc_map_vrma(struct kvm_vcpu *vcpu, struct kvm_memory_slot *memslot)
* is available and use it.
*/
hash = (hash << 3) + 7;
hp_v = HPTE_V_1TB_SEG | (VRMA_VSID << (40 - 16)) |
(i << (VRMA_PAGE_ORDER - 16)) | HPTE_V_BOLTED |
HPTE_V_LARGE | HPTE_V_VALID;
hp_r = addr | HPTE_R_R | HPTE_R_C | HPTE_R_M | PP_RWXX;
hp_v = hp0 | ((addr >> 16) & ~0x7fUL);
hp_r = hp1 | addr;
ret = kvmppc_virtmode_h_enter(vcpu, H_EXACT, hash, hp_v, hp_r);
if (ret != H_SUCCESS) {
pr_err("KVM: map_vrma at %lx failed, ret=%ld\n",
Expand Down Expand Up @@ -176,48 +191,72 @@ static void kvmppc_mmu_book3s_64_hv_reset_msr(struct kvm_vcpu *vcpu)
* one already in the kvm->arch.slot_phys[][] arrays.
*/
static long kvmppc_get_guest_page(struct kvm *kvm, unsigned long gfn,
struct kvm_memory_slot *memslot)
struct kvm_memory_slot *memslot,
unsigned long psize)
{
unsigned long start;
long np;
struct page *page, *pages[1];
long np, err;
struct page *page, *hpage, *pages[1];
unsigned long s, pgsize;
unsigned long *physp;
unsigned long pfn, i;
unsigned int got, pgorder;
unsigned long pfn, i, npages;

physp = kvm->arch.slot_phys[memslot->id];
if (!physp)
return -EINVAL;
i = (gfn - memslot->base_gfn) >> (kvm->arch.ram_porder - PAGE_SHIFT);
if (physp[i])
if (physp[gfn - memslot->base_gfn])
return 0;

page = NULL;
pgsize = psize;
start = gfn_to_hva_memslot(memslot, gfn);

/* Instantiate and get the page we want access to */
np = get_user_pages_fast(start, 1, 1, pages);
if (np != 1)
return -EINVAL;
page = pages[0];

/* Check it's a 16MB page */
if (!PageHead(page) ||
compound_order(page) != (kvm->arch.ram_porder - PAGE_SHIFT)) {
pr_err("page at %lx isn't 16MB (o=%d)\n",
start, compound_order(page));
put_page(page);
return -EINVAL;
got = KVMPPC_GOT_PAGE;

/* See if this is a large page */
s = PAGE_SIZE;
if (PageHuge(page)) {
hpage = compound_head(page);
s <<= compound_order(hpage);
/* Get the whole large page if slot alignment is ok */
if (s > psize && slot_is_aligned(memslot, s) &&
!(memslot->userspace_addr & (s - 1))) {
start &= ~(s - 1);
pgsize = s;
page = hpage;
}
}
err = -EINVAL;
if (s < psize)
goto out;
pfn = page_to_pfn(page);

npages = pgsize >> PAGE_SHIFT;
pgorder = __ilog2(npages);
physp += (gfn - memslot->base_gfn) & ~(npages - 1);
spin_lock(&kvm->arch.slot_phys_lock);
if (!physp[i])
physp[i] = (pfn << PAGE_SHIFT) | KVMPPC_GOT_PAGE;
else
put_page(page);
for (i = 0; i < npages; ++i) {
if (!physp[i]) {
physp[i] = ((pfn + i) << PAGE_SHIFT) + got + pgorder;
got = 0;
}
}
spin_unlock(&kvm->arch.slot_phys_lock);
err = 0;

return 0;
out:
if (got) {
if (PageHuge(page))
page = compound_head(page);
put_page(page);
}
return err;
}

/*
Expand All @@ -242,7 +281,9 @@ long kvmppc_virtmode_h_enter(struct kvm_vcpu *vcpu, unsigned long flags,
memslot = gfn_to_memslot(kvm, gfn);
if (!memslot || (memslot->flags & KVM_MEMSLOT_INVALID))
return H_PARAMETER;
if (kvmppc_get_guest_page(kvm, gfn, memslot) < 0)
if (!slot_is_aligned(memslot, psize))
return H_PARAMETER;
if (kvmppc_get_guest_page(kvm, gfn, memslot, psize) < 0)
return H_PARAMETER;

preempt_disable();
Expand All @@ -269,8 +310,8 @@ void *kvmppc_pin_guest_page(struct kvm *kvm, unsigned long gpa,
struct kvm_memory_slot *memslot;
unsigned long gfn = gpa >> PAGE_SHIFT;
struct page *page;
unsigned long offset;
unsigned long pfn, pa;
unsigned long psize, offset;
unsigned long pa;
unsigned long *physp;

memslot = gfn_to_memslot(kvm, gfn);
Expand All @@ -279,20 +320,23 @@ void *kvmppc_pin_guest_page(struct kvm *kvm, unsigned long gpa,
physp = kvm->arch.slot_phys[memslot->id];
if (!physp)
return NULL;
physp += (gfn - memslot->base_gfn) >>
(kvm->arch.ram_porder - PAGE_SHIFT);
physp += gfn - memslot->base_gfn;
pa = *physp;
if (!pa) {
if (kvmppc_get_guest_page(kvm, gfn, memslot) < 0)
if (kvmppc_get_guest_page(kvm, gfn, memslot, PAGE_SIZE) < 0)
return NULL;
pa = *physp;
}
pfn = pa >> PAGE_SHIFT;
page = pfn_to_page(pfn);
page = pfn_to_page(pa >> PAGE_SHIFT);
psize = PAGE_SIZE;
if (PageHuge(page)) {
page = compound_head(page);
psize <<= compound_order(page);
}
get_page(page);
offset = gpa & (kvm->arch.ram_psize - 1);
offset = gpa & (psize - 1);
if (nb_ret)
*nb_ret = kvm->arch.ram_psize - offset;
*nb_ret = psize - offset;
return page_address(page) + offset;
}

Expand Down
57 changes: 31 additions & 26 deletions arch/powerpc/kvm/book3s_hv.c
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Original file line number Diff line number Diff line change
Expand Up @@ -51,8 +51,6 @@
#include <linux/highmem.h>
#include <linux/hugetlb.h>

#define LARGE_PAGE_ORDER 24 /* 16MB pages */

/* #define EXIT_DEBUG */
/* #define EXIT_DEBUG_SIMPLE */
/* #define EXIT_DEBUG_INT */
Expand Down Expand Up @@ -1074,24 +1072,26 @@ long kvm_vm_ioctl_allocate_rma(struct kvm *kvm, struct kvm_allocate_rma *ret)
return fd;
}

static unsigned long slb_pgsize_encoding(unsigned long psize)
{
unsigned long senc = 0;

if (psize > 0x1000) {
senc = SLB_VSID_L;
if (psize == 0x10000)
senc |= SLB_VSID_LP_01;
}
return senc;
}

int kvmppc_core_prepare_memory_region(struct kvm *kvm,
struct kvm_userspace_memory_region *mem)
{
unsigned long psize;
unsigned long npages;
unsigned long *phys;

/* For now, only allow 16MB-aligned slots */
psize = kvm->arch.ram_psize;
if ((mem->memory_size & (psize - 1)) ||
(mem->guest_phys_addr & (psize - 1))) {
pr_err("bad memory_size=%llx @ %llx\n",
mem->memory_size, mem->guest_phys_addr);
return -EINVAL;
}

/* Allocate a slot_phys array */
npages = mem->memory_size >> kvm->arch.ram_porder;
npages = mem->memory_size >> PAGE_SHIFT;
phys = kvm->arch.slot_phys[mem->slot];
if (!phys) {
phys = vzalloc(npages * sizeof(unsigned long));
Expand Down Expand Up @@ -1119,6 +1119,8 @@ static void unpin_slot(struct kvm *kvm, int slot_id)
continue;
pfn = physp[j] >> PAGE_SHIFT;
page = pfn_to_page(pfn);
if (PageHuge(page))
page = compound_head(page);
SetPageDirty(page);
put_page(page);
}
Expand All @@ -1141,12 +1143,12 @@ static int kvmppc_hv_setup_rma(struct kvm_vcpu *vcpu)
unsigned long hva;
struct kvm_memory_slot *memslot;
struct vm_area_struct *vma;
unsigned long lpcr;
unsigned long lpcr, senc;
unsigned long psize, porder;
unsigned long rma_size;
unsigned long rmls;
unsigned long *physp;
unsigned long i, npages, pa;
unsigned long i, npages;

mutex_lock(&kvm->lock);
if (kvm->arch.rma_setup_done)
Expand All @@ -1168,8 +1170,7 @@ static int kvmppc_hv_setup_rma(struct kvm_vcpu *vcpu)
goto up_out;

psize = vma_kernel_pagesize(vma);
if (psize != kvm->arch.ram_psize)
goto up_out;
porder = __ilog2(psize);

/* Is this one of our preallocated RMAs? */
if (vma->vm_file && vma->vm_file->f_op == &kvm_rma_fops &&
Expand All @@ -1186,13 +1187,20 @@ static int kvmppc_hv_setup_rma(struct kvm_vcpu *vcpu)
goto out;
}

/* We can handle 4k, 64k or 16M pages in the VRMA */
err = -EINVAL;
if (!(psize == 0x1000 || psize == 0x10000 ||
psize == 0x1000000))
goto out;

/* Update VRMASD field in the LPCR */
lpcr = kvm->arch.lpcr & ~(0x1fUL << LPCR_VRMASD_SH);
lpcr |= LPCR_VRMA_L;
senc = slb_pgsize_encoding(psize);
lpcr = kvm->arch.lpcr & ~LPCR_VRMASD;
lpcr |= senc << (LPCR_VRMASD_SH - 4);
kvm->arch.lpcr = lpcr;

/* Create HPTEs in the hash page table for the VRMA */
kvmppc_map_vrma(vcpu, memslot);
kvmppc_map_vrma(vcpu, memslot, porder);

} else {
/* Set up to use an RMO region */
Expand Down Expand Up @@ -1231,13 +1239,12 @@ static int kvmppc_hv_setup_rma(struct kvm_vcpu *vcpu)
ri->base_pfn << PAGE_SHIFT, rma_size, lpcr);

/* Initialize phys addrs of pages in RMO */
porder = kvm->arch.ram_porder;
npages = rma_size >> porder;
pa = ri->base_pfn << PAGE_SHIFT;
npages = ri->npages;
porder = __ilog2(npages);
physp = kvm->arch.slot_phys[memslot->id];
spin_lock(&kvm->arch.slot_phys_lock);
for (i = 0; i < npages; ++i)
physp[i] = pa + (i << porder);
physp[i] = ((ri->base_pfn + i) << PAGE_SHIFT) + porder;
spin_unlock(&kvm->arch.slot_phys_lock);
}

Expand Down Expand Up @@ -1266,8 +1273,6 @@ int kvmppc_core_init_vm(struct kvm *kvm)

INIT_LIST_HEAD(&kvm->arch.spapr_tce_tables);

kvm->arch.ram_psize = 1ul << LARGE_PAGE_ORDER;
kvm->arch.ram_porder = LARGE_PAGE_ORDER;
kvm->arch.rma = NULL;

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