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Updates for KVM/ARM, take 2 including:

Browse Source 
- Transparent Huge Pages and hugetlbfs support for KVM/ARM
  - Yield CPU when guest executes WFE to speed up CPU overcommit
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Merge tag 'kvm-arm-for-3.13-2' of git://git.linaro.org/people/cdall/linux-kvm-arm into kvm-queue

Updates for KVM/ARM, take 2 including:
 - Transparent Huge Pages and hugetlbfs support for KVM/ARM
 - Yield CPU when guest executes WFE to speed up CPU overcommit
This commit is contained in:
Paolo Bonzini 2013-10-28 13:15:55 +01:00
commit 5bb3398dd2
8 changed files with 230 additions and 52 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
arch/arm/include/asm/kvm_arm.h
View File

@ -57,6 +57,7 @@
* TSC: Trap SMC
* TSW: Trap cache operations by set/way
* TWI: Trap WFI
* TWE: Trap WFE
* TIDCP: Trap L2CTLR/L2ECTLR
* BSU_IS: Upgrade barriers to the inner shareable domain
* FB: Force broadcast of all maintainance operations
@ -67,7 +68,7 @@
*/
#define HCR_GUEST_MASK (HCR_TSC | HCR_TSW | HCR_TWI | HCR_VM | HCR_BSU_IS | \
HCR_FB | HCR_TAC | HCR_AMO | HCR_IMO | HCR_FMO | \
HCR_SWIO | HCR_TIDCP)
HCR_TWE | HCR_SWIO | HCR_TIDCP)
#define HCR_VIRT_EXCP_MASK (HCR_VA | HCR_VI | HCR_VF)
/* System Control Register (SCTLR) bits */
@ -208,6 +209,8 @@
#define HSR_EC_DABT (0x24)
#define HSR_EC_DABT_HYP (0x25)
#define HSR_WFI_IS_WFE (1U << 0)
#define HSR_HVC_IMM_MASK ((1UL << 16) - 1)
#define HSR_DABT_S1PTW (1U << 7)

17
arch/arm/include/asm/kvm_mmu.h
View File

@ -62,6 +62,12 @@ phys_addr_t kvm_get_idmap_vector(void);
int kvm_mmu_init(void);
void kvm_clear_hyp_idmap(void);
static inline void kvm_set_pmd(pmd_t *pmd, pmd_t new_pmd)
{
*pmd = new_pmd;
flush_pmd_entry(pmd);
}
static inline void kvm_set_pte(pte_t *pte, pte_t new_pte)
{
*pte = new_pte;
@ -103,9 +109,15 @@ static inline void kvm_set_s2pte_writable(pte_t *pte)
pte_val(*pte) |= L_PTE_S2_RDWR;
}
static inline void kvm_set_s2pmd_writable(pmd_t *pmd)
{
pmd_val(*pmd) |= L_PMD_S2_RDWR;
}
struct kvm;
static inline void coherent_icache_guest_page(struct kvm *kvm, gfn_t gfn)
static inline void coherent_icache_guest_page(struct kvm *kvm, hva_t hva,
unsigned long size)
{
/*
* If we are going to insert an instruction page and the icache is
@ -120,8 +132,7 @@ static inline void coherent_icache_guest_page(struct kvm *kvm, gfn_t gfn)
* need any kind of flushing (DDI 0406C.b - Page B3-1392).
*/
if (icache_is_pipt()) {
unsigned long hva = gfn_to_hva(kvm, gfn);
__cpuc_coherent_user_range(hva, hva + PAGE_SIZE);
__cpuc_coherent_user_range(hva, hva + size);
} else if (!icache_is_vivt_asid_tagged()) {
/* any kind of VIPT cache */
__flush_icache_all();

2
arch/arm/include/asm/pgtable-3level.h
View File

@ -126,6 +126,8 @@
#define L_PTE_S2_RDONLY (_AT(pteval_t, 1) << 6) /* HAP[1] */
#define L_PTE_S2_RDWR (_AT(pteval_t, 3) << 6) /* HAP[2:1] */
#define L_PMD_S2_RDWR (_AT(pmdval_t, 3) << 6) /* HAP[2:1] */
/*
* Hyp-mode PL2 PTE definitions for LPAE.
*/

1
arch/arm/kvm/Kconfig
View File

@ -20,6 +20,7 @@ config KVM
bool "Kernel-based Virtual Machine (KVM) support"
select PREEMPT_NOTIFIERS
select ANON_INODES
select HAVE_KVM_CPU_RELAX_INTERCEPT
select KVM_MMIO
select KVM_ARM_HOST
depends on ARM_VIRT_EXT && ARM_LPAE

20
arch/arm/kvm/handle_exit.c
View File

@ -73,23 +73,29 @@ static int handle_dabt_hyp(struct kvm_vcpu *vcpu, struct kvm_run *run)
}
/**
* kvm_handle_wfi - handle a wait-for-interrupts instruction executed by a guest
* kvm_handle_wfx - handle a WFI or WFE instructions trapped in guests
* @vcpu: the vcpu pointer
* @run: the kvm_run structure pointer
*
* Simply sets the wait_for_interrupts flag on the vcpu structure, which will
* halt execution of world-switches and schedule other host processes until
* there is an incoming IRQ or FIQ to the VM.
* WFE: Yield the CPU and come back to this vcpu when the scheduler
* decides to.
* WFI: Simply call kvm_vcpu_block(), which will halt execution of
* world-switches and schedule other host processes until there is an
* incoming IRQ or FIQ to the VM.
*/
static int kvm_handle_wfi(struct kvm_vcpu *vcpu, struct kvm_run *run)
static int kvm_handle_wfx(struct kvm_vcpu *vcpu, struct kvm_run *run)
{
trace_kvm_wfi(*vcpu_pc(vcpu));
kvm_vcpu_block(vcpu);
if (kvm_vcpu_get_hsr(vcpu) & HSR_WFI_IS_WFE)
kvm_vcpu_on_spin(vcpu);
else
kvm_vcpu_block(vcpu);
return 1;
}
static exit_handle_fn arm_exit_handlers[] = {
[HSR_EC_WFI] = kvm_handle_wfi,
[HSR_EC_WFI] = kvm_handle_wfx,
[HSR_EC_CP15_32] = kvm_handle_cp15_32,
[HSR_EC_CP15_64] = kvm_handle_cp15_64,
[HSR_EC_CP14_MR] = kvm_handle_cp14_access,

223
arch/arm/kvm/mmu.c
View File

@ -19,6 +19,7 @@
#include <linux/mman.h>
#include <linux/kvm_host.h>
#include <linux/io.h>
#include <linux/hugetlb.h>
#include <trace/events/kvm.h>
#include <asm/pgalloc.h>
#include <asm/cacheflush.h>
@ -41,6 +42,8 @@ static unsigned long hyp_idmap_start;
static unsigned long hyp_idmap_end;
static phys_addr_t hyp_idmap_vector;
#define kvm_pmd_huge(_x) (pmd_huge(_x) || pmd_trans_huge(_x))
static void kvm_tlb_flush_vmid_ipa(struct kvm *kvm, phys_addr_t ipa)
{
/*
@ -93,19 +96,29 @@ static bool page_empty(void *ptr)
static void clear_pud_entry(struct kvm *kvm, pud_t *pud, phys_addr_t addr)
{
pmd_t *pmd_table = pmd_offset(pud, 0);
pud_clear(pud);
kvm_tlb_flush_vmid_ipa(kvm, addr);
pmd_free(NULL, pmd_table);
if (pud_huge(*pud)) {
pud_clear(pud);
kvm_tlb_flush_vmid_ipa(kvm, addr);
} else {
pmd_t *pmd_table = pmd_offset(pud, 0);
pud_clear(pud);
kvm_tlb_flush_vmid_ipa(kvm, addr);
pmd_free(NULL, pmd_table);
}
put_page(virt_to_page(pud));
}
static void clear_pmd_entry(struct kvm *kvm, pmd_t *pmd, phys_addr_t addr)
{
pte_t *pte_table = pte_offset_kernel(pmd, 0);
pmd_clear(pmd);
kvm_tlb_flush_vmid_ipa(kvm, addr);
pte_free_kernel(NULL, pte_table);
if (kvm_pmd_huge(*pmd)) {
pmd_clear(pmd);
kvm_tlb_flush_vmid_ipa(kvm, addr);
} else {
pte_t *pte_table = pte_offset_kernel(pmd, 0);
pmd_clear(pmd);
kvm_tlb_flush_vmid_ipa(kvm, addr);
pte_free_kernel(NULL, pte_table);
}
put_page(virt_to_page(pmd));
}
@ -136,18 +149,32 @@ static void unmap_range(struct kvm *kvm, pgd_t *pgdp,
continue;
}
if (pud_huge(*pud)) {
/*
* If we are dealing with a huge pud, just clear it and
* move on.
*/
clear_pud_entry(kvm, pud, addr);
addr = pud_addr_end(addr, end);
continue;
}
pmd = pmd_offset(pud, addr);
if (pmd_none(*pmd)) {
addr = pmd_addr_end(addr, end);
continue;
}
pte = pte_offset_kernel(pmd, addr);
clear_pte_entry(kvm, pte, addr);
next = addr + PAGE_SIZE;
if (!kvm_pmd_huge(*pmd)) {
pte = pte_offset_kernel(pmd, addr);
clear_pte_entry(kvm, pte, addr);
next = addr + PAGE_SIZE;
}
/* If we emptied the pte, walk back up the ladder */
if (page_empty(pte)) {
/*
* If the pmd entry is to be cleared, walk back up the ladder
*/
if (kvm_pmd_huge(*pmd) || page_empty(pte)) {
clear_pmd_entry(kvm, pmd, addr);
next = pmd_addr_end(addr, end);
if (page_empty(pmd) && !page_empty(pud)) {
@ -420,29 +447,71 @@ void kvm_free_stage2_pgd(struct kvm *kvm)
kvm->arch.pgd = NULL;
}
static int stage2_set_pte(struct kvm *kvm, struct kvm_mmu_memory_cache *cache,
phys_addr_t addr, const pte_t *new_pte, bool iomap)
static pmd_t *stage2_get_pmd(struct kvm *kvm, struct kvm_mmu_memory_cache *cache,
phys_addr_t addr)
{
pgd_t *pgd;
pud_t *pud;
pmd_t *pmd;
pte_t *pte, old_pte;
/* Create 2nd stage page table mapping - Level 1 */
pgd = kvm->arch.pgd + pgd_index(addr);
pud = pud_offset(pgd, addr);
if (pud_none(*pud)) {
if (!cache)
return 0; /* ignore calls from kvm_set_spte_hva */
return NULL;
pmd = mmu_memory_cache_alloc(cache);
pud_populate(NULL, pud, pmd);
get_page(virt_to_page(pud));
}
pmd = pmd_offset(pud, addr);
return pmd_offset(pud, addr);
}
/* Create 2nd stage page table mapping - Level 2 */
static int stage2_set_pmd_huge(struct kvm *kvm, struct kvm_mmu_memory_cache
*cache, phys_addr_t addr, const pmd_t *new_pmd)
{
pmd_t *pmd, old_pmd;
pmd = stage2_get_pmd(kvm, cache, addr);
VM_BUG_ON(!pmd);
/*
* Mapping in huge pages should only happen through a fault. If a
* page is merged into a transparent huge page, the individual
* subpages of that huge page should be unmapped through MMU
* notifiers before we get here.
*
* Merging of CompoundPages is not supported; they should become
* splitting first, unmapped, merged, and mapped back in on-demand.
*/
VM_BUG_ON(pmd_present(*pmd) && pmd_pfn(*pmd) != pmd_pfn(*new_pmd));
old_pmd = *pmd;
kvm_set_pmd(pmd, *new_pmd);
if (pmd_present(old_pmd))
kvm_tlb_flush_vmid_ipa(kvm, addr);
else
get_page(virt_to_page(pmd));
return 0;
}
static int stage2_set_pte(struct kvm *kvm, struct kvm_mmu_memory_cache *cache,
phys_addr_t addr, const pte_t *new_pte, bool iomap)
{
pmd_t *pmd;
pte_t *pte, old_pte;
/* Create stage-2 page table mapping - Level 1 */
pmd = stage2_get_pmd(kvm, cache, addr);
if (!pmd) {
/*
* Ignore calls from kvm_set_spte_hva for unallocated
* address ranges.
*/
return 0;
}
/* Create stage-2 page mappings - Level 2 */
if (pmd_none(*pmd)) {
if (!cache)
return 0; /* ignore calls from kvm_set_spte_hva */
@ -507,16 +576,60 @@ int kvm_phys_addr_ioremap(struct kvm *kvm, phys_addr_t guest_ipa,
return ret;
}
static bool transparent_hugepage_adjust(pfn_t *pfnp, phys_addr_t *ipap)
{
pfn_t pfn = *pfnp;
gfn_t gfn = *ipap >> PAGE_SHIFT;
if (PageTransCompound(pfn_to_page(pfn))) {
unsigned long mask;
/*
* The address we faulted on is backed by a transparent huge
* page. However, because we map the compound huge page and
* not the individual tail page, we need to transfer the
* refcount to the head page. We have to be careful that the
* THP doesn't start to split while we are adjusting the
* refcounts.
*
* We are sure this doesn't happen, because mmu_notifier_retry
* was successful and we are holding the mmu_lock, so if this
* THP is trying to split, it will be blocked in the mmu
* notifier before touching any of the pages, specifically
* before being able to call __split_huge_page_refcount().
*
* We can therefore safely transfer the refcount from PG_tail
* to PG_head and switch the pfn from a tail page to the head
* page accordingly.
*/
mask = PTRS_PER_PMD - 1;
VM_BUG_ON((gfn & mask) != (pfn & mask));
if (pfn & mask) {
*ipap &= PMD_MASK;
kvm_release_pfn_clean(pfn);
pfn &= ~mask;
kvm_get_pfn(pfn);
*pfnp = pfn;
}
return true;
}
return false;
}
static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
gfn_t gfn, struct kvm_memory_slot *memslot,
struct kvm_memory_slot *memslot,
unsigned long fault_status)
{
pte_t new_pte;
pfn_t pfn;
int ret;
bool write_fault, writable;
bool write_fault, writable, hugetlb = false, force_pte = false;
unsigned long mmu_seq;
gfn_t gfn = fault_ipa >> PAGE_SHIFT;
unsigned long hva = gfn_to_hva(vcpu->kvm, gfn);
struct kvm *kvm = vcpu->kvm;
struct kvm_mmu_memory_cache *memcache = &vcpu->arch.mmu_page_cache;
struct vm_area_struct *vma;
pfn_t pfn;
write_fault = kvm_is_write_fault(kvm_vcpu_get_hsr(vcpu));
if (fault_status == FSC_PERM && !write_fault) {
@ -524,6 +637,26 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
return -EFAULT;
}
/* Let's check if we will get back a huge page backed by hugetlbfs */
down_read(&current->mm->mmap_sem);
vma = find_vma_intersection(current->mm, hva, hva + 1);
if (is_vm_hugetlb_page(vma)) {
hugetlb = true;
gfn = (fault_ipa & PMD_MASK) >> PAGE_SHIFT;
} else {
/*
* Pages belonging to VMAs not aligned to the PMD mapping
* granularity cannot be mapped using block descriptors even
* if the pages belong to a THP for the process, because the
* stage-2 block descriptor will cover more than a single THP
* and we loose atomicity for unmapping, updates, and splits
* of the THP or other pages in the stage-2 block range.
*/
if (vma->vm_start & ~PMD_MASK)
force_pte = true;
}
up_read(&current->mm->mmap_sem);
/* We need minimum second+third level pages */
ret = mmu_topup_memory_cache(memcache, 2, KVM_NR_MEM_OBJS);
if (ret)
@ -541,26 +674,40 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
*/
smp_rmb();
pfn = gfn_to_pfn_prot(vcpu->kvm, gfn, write_fault, &writable);
pfn = gfn_to_pfn_prot(kvm, gfn, write_fault, &writable);
if (is_error_pfn(pfn))
return -EFAULT;
new_pte = pfn_pte(pfn, PAGE_S2);
coherent_icache_guest_page(vcpu->kvm, gfn);
spin_lock(&vcpu->kvm->mmu_lock);
if (mmu_notifier_retry(vcpu->kvm, mmu_seq))
spin_lock(&kvm->mmu_lock);
if (mmu_notifier_retry(kvm, mmu_seq))
goto out_unlock;
if (writable) {
kvm_set_s2pte_writable(&new_pte);
kvm_set_pfn_dirty(pfn);
if (!hugetlb && !force_pte)
hugetlb = transparent_hugepage_adjust(&pfn, &fault_ipa);
if (hugetlb) {
pmd_t new_pmd = pfn_pmd(pfn, PAGE_S2);
new_pmd = pmd_mkhuge(new_pmd);
if (writable) {
kvm_set_s2pmd_writable(&new_pmd);
kvm_set_pfn_dirty(pfn);
}
coherent_icache_guest_page(kvm, hva & PMD_MASK, PMD_SIZE);
ret = stage2_set_pmd_huge(kvm, memcache, fault_ipa, &new_pmd);
} else {
pte_t new_pte = pfn_pte(pfn, PAGE_S2);
if (writable) {
kvm_set_s2pte_writable(&new_pte);
kvm_set_pfn_dirty(pfn);
}
coherent_icache_guest_page(kvm, hva, PAGE_SIZE);
ret = stage2_set_pte(kvm, memcache, fault_ipa, &new_pte, false);
}
stage2_set_pte(vcpu->kvm, memcache, fault_ipa, &new_pte, false);
out_unlock:
spin_unlock(&vcpu->kvm->mmu_lock);
spin_unlock(&kvm->mmu_lock);
kvm_release_pfn_clean(pfn);
return 0;
return ret;
}
/**
@ -629,7 +776,7 @@ int kvm_handle_guest_abort(struct kvm_vcpu *vcpu, struct kvm_run *run)
memslot = gfn_to_memslot(vcpu->kvm, gfn);
ret = user_mem_abort(vcpu, fault_ipa, gfn, memslot, fault_status);
ret = user_mem_abort(vcpu, fault_ipa, memslot, fault_status);
if (ret == 0)
ret = 1;
out_unlock:

12
arch/arm64/include/asm/kvm_mmu.h
View File

@ -91,6 +91,7 @@ int kvm_mmu_init(void);
void kvm_clear_hyp_idmap(void);
#define kvm_set_pte(ptep, pte) set_pte(ptep, pte)
#define kvm_set_pmd(pmdp, pmd) set_pmd(pmdp, pmd)
static inline bool kvm_is_write_fault(unsigned long esr)
{
@ -116,13 +117,18 @@ static inline void kvm_set_s2pte_writable(pte_t *pte)
pte_val(*pte) |= PTE_S2_RDWR;
}
static inline void kvm_set_s2pmd_writable(pmd_t *pmd)
{
pmd_val(*pmd) |= PMD_S2_RDWR;
}
struct kvm;
static inline void coherent_icache_guest_page(struct kvm *kvm, gfn_t gfn)
static inline void coherent_icache_guest_page(struct kvm *kvm, hva_t hva,
unsigned long size)
{
if (!icache_is_aliasing()) { /* PIPT */
unsigned long hva = gfn_to_hva(kvm, gfn);
flush_icache_range(hva, hva + PAGE_SIZE);
flush_icache_range(hva, hva + size);
} else if (!icache_is_aivivt()) { /* non ASID-tagged VIVT */
/* any kind of VIPT cache */
__flush_icache_all();

2
arch/arm64/include/asm/pgtable-hwdef.h
View File

@ -85,6 +85,8 @@
#define PTE_S2_RDONLY (_AT(pteval_t, 1) << 6) /* HAP[2:1] */
#define PTE_S2_RDWR (_AT(pteval_t, 3) << 6) /* HAP[2:1] */
#define PMD_S2_RDWR (_AT(pmdval_t, 3) << 6) /* HAP[2:1] */
/*
* Memory Attribute override for Stage-2 (MemAttr[3:0])
*/