| Message ID | 20221025151344.3784230-7-chao.p.peng@linux.intel.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | KVM: mm: fd-based approach for supporting KVM | expand |
On Tue, Oct 25, 2022 at 11:13:42PM +0800, Chao Peng <chao.p.peng@linux.intel.com> wrote: > When private/shared memory are mixed in a large page, the lpage_info may > not be accurate and should be updated with this mixed info. A large page > has mixed pages can't be really mapped as large page since its > private/shared pages are from different physical memory. > > Update lpage_info when private/shared memory attribute is changed. If > both private and shared pages are within a large page region, it can't > be mapped as large page. It's a bit challenge to track the mixed > info in a 'count' like variable, this patch instead reserves a bit in > 'disallow_lpage' to indicate a large page has mixed private/share pages. > > Signed-off-by: Chao Peng <chao.p.peng@linux.intel.com> > --- > arch/x86/include/asm/kvm_host.h | 8 +++ > arch/x86/kvm/mmu/mmu.c | 112 +++++++++++++++++++++++++++++++- > arch/x86/kvm/x86.c | 2 + > include/linux/kvm_host.h | 19 ++++++ > virt/kvm/kvm_main.c | 16 +++-- > 5 files changed, 152 insertions(+), 5 deletions(-) > ... > diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c > index 33b1aec44fb8..67a9823a8c35 100644 > --- a/arch/x86/kvm/mmu/mmu.c > +++ b/arch/x86/kvm/mmu/mmu.c ... > @@ -6910,3 +6915,108 @@ void kvm_mmu_pre_destroy_vm(struct kvm *kvm) > if (kvm->arch.nx_lpage_recovery_thread) > kthread_stop(kvm->arch.nx_lpage_recovery_thread); > } > + > +static inline bool linfo_is_mixed(struct kvm_lpage_info *linfo) > +{ > + return linfo->disallow_lpage & KVM_LPAGE_PRIVATE_SHARED_MIXED; > +} > + > +static inline void linfo_update_mixed(struct kvm_lpage_info *linfo, bool mixed) > +{ > + if (mixed) > + linfo->disallow_lpage |= KVM_LPAGE_PRIVATE_SHARED_MIXED; > + else > + linfo->disallow_lpage &= ~KVM_LPAGE_PRIVATE_SHARED_MIXED; > +} > + > +static bool mem_attr_is_mixed_2m(struct kvm *kvm, unsigned int attr, > + gfn_t start, gfn_t end) > +{ > + XA_STATE(xas, &kvm->mem_attr_array, start); > + gfn_t gfn = start; > + void *entry; > + bool shared = attr == KVM_MEM_ATTR_SHARED; > + bool mixed = false; > + > + rcu_read_lock(); > + entry = xas_load(&xas); > + while (gfn < end) { > + if (xas_retry(&xas, entry)) > + continue; > + > + KVM_BUG_ON(gfn != xas.xa_index, kvm); > + > + if ((entry && !shared) || (!entry && shared)) { > + mixed = true; > + goto out; nitpick: goto isn't needed. break should work. > + } > + > + entry = xas_next(&xas); > + gfn++; > + } > +out: > + rcu_read_unlock(); > + return mixed; > +} > + > +static bool mem_attr_is_mixed(struct kvm *kvm, struct kvm_memory_slot *slot, > + int level, unsigned int attr, > + gfn_t start, gfn_t end) > +{ > + unsigned long gfn; > + void *entry; > + > + if (level == PG_LEVEL_2M) > + return mem_attr_is_mixed_2m(kvm, attr, start, end); > + > + entry = xa_load(&kvm->mem_attr_array, start); > + for (gfn = start; gfn < end; gfn += KVM_PAGES_PER_HPAGE(level - 1)) { > + if (linfo_is_mixed(lpage_info_slot(gfn, slot, level - 1))) > + return true; > + if (xa_load(&kvm->mem_attr_array, gfn) != entry) > + return true; > + } > + return false; > +} > + > +void kvm_arch_update_mem_attr(struct kvm *kvm, struct kvm_memory_slot *slot, > + unsigned int attr, gfn_t start, gfn_t end) > +{ > + > + unsigned long lpage_start, lpage_end; > + unsigned long gfn, pages, mask; > + int level; > + > + WARN_ONCE(!(attr & (KVM_MEM_ATTR_PRIVATE | KVM_MEM_ATTR_SHARED)), > + "Unsupported mem attribute.\n"); > + > + /* > + * The sequence matters here: we update the higher level basing on the > + * lower level's scanning result. > + */ > + for (level = PG_LEVEL_2M; level <= KVM_MAX_HUGEPAGE_LEVEL; level++) { > + pages = KVM_PAGES_PER_HPAGE(level); > + mask = ~(pages - 1); nitpick: KVM_HPAGE_MASK(level). Maybe matter of preference. > + lpage_start = max(start & mask, slot->base_gfn); > + lpage_end = (end - 1) & mask; > + > + /* > + * We only need to scan the head and tail page, for middle pages > + * we know they are not mixed. > + */ > + linfo_update_mixed(lpage_info_slot(lpage_start, slot, level), > + mem_attr_is_mixed(kvm, slot, level, attr, > + lpage_start, start)); > + > + if (lpage_start == lpage_end) > + return; > + > + for (gfn = lpage_start + pages; gfn < lpage_end; gfn += pages) > + linfo_update_mixed(lpage_info_slot(gfn, slot, level), > + false); > + > + linfo_update_mixed(lpage_info_slot(lpage_end, slot, level), > + mem_attr_is_mixed(kvm, slot, level, attr, > + end, lpage_end + pages)); > + } > +}
On Wed, Oct 26, 2022 at 01:46:20PM -0700, Isaku Yamahata wrote: > On Tue, Oct 25, 2022 at 11:13:42PM +0800, > Chao Peng <chao.p.peng@linux.intel.com> wrote: > > > When private/shared memory are mixed in a large page, the lpage_info may > > not be accurate and should be updated with this mixed info. A large page > > has mixed pages can't be really mapped as large page since its > > private/shared pages are from different physical memory. > > > > Update lpage_info when private/shared memory attribute is changed. If > > both private and shared pages are within a large page region, it can't > > be mapped as large page. It's a bit challenge to track the mixed > > info in a 'count' like variable, this patch instead reserves a bit in > > 'disallow_lpage' to indicate a large page has mixed private/share pages. > > > > Signed-off-by: Chao Peng <chao.p.peng@linux.intel.com> > > --- > > arch/x86/include/asm/kvm_host.h | 8 +++ > > arch/x86/kvm/mmu/mmu.c | 112 +++++++++++++++++++++++++++++++- > > arch/x86/kvm/x86.c | 2 + > > include/linux/kvm_host.h | 19 ++++++ > > virt/kvm/kvm_main.c | 16 +++-- > > 5 files changed, 152 insertions(+), 5 deletions(-) > > > ... > > diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c > > index 33b1aec44fb8..67a9823a8c35 100644 > > --- a/arch/x86/kvm/mmu/mmu.c > > +++ b/arch/x86/kvm/mmu/mmu.c > ... > > @@ -6910,3 +6915,108 @@ void kvm_mmu_pre_destroy_vm(struct kvm *kvm) > > if (kvm->arch.nx_lpage_recovery_thread) > > kthread_stop(kvm->arch.nx_lpage_recovery_thread); > > } > > + > > +static inline bool linfo_is_mixed(struct kvm_lpage_info *linfo) > > +{ > > + return linfo->disallow_lpage & KVM_LPAGE_PRIVATE_SHARED_MIXED; > > +} > > + > > +static inline void linfo_update_mixed(struct kvm_lpage_info *linfo, bool mixed) > > +{ > > + if (mixed) > > + linfo->disallow_lpage |= KVM_LPAGE_PRIVATE_SHARED_MIXED; > > + else > > + linfo->disallow_lpage &= ~KVM_LPAGE_PRIVATE_SHARED_MIXED; > > +} > > + > > +static bool mem_attr_is_mixed_2m(struct kvm *kvm, unsigned int attr, > > + gfn_t start, gfn_t end) > > +{ > > + XA_STATE(xas, &kvm->mem_attr_array, start); > > + gfn_t gfn = start; > > + void *entry; > > + bool shared = attr == KVM_MEM_ATTR_SHARED; > > + bool mixed = false; > > + > > + rcu_read_lock(); > > + entry = xas_load(&xas); > > + while (gfn < end) { > > + if (xas_retry(&xas, entry)) > > + continue; > > + > > + KVM_BUG_ON(gfn != xas.xa_index, kvm); > > + > > + if ((entry && !shared) || (!entry && shared)) { > > + mixed = true; > > + goto out; > > nitpick: goto isn't needed. break should work. Thanks. > > > + } > > + > > + entry = xas_next(&xas); > > + gfn++; > > + } > > +out: > > + rcu_read_unlock(); > > + return mixed; > > +} > > + > > +static bool mem_attr_is_mixed(struct kvm *kvm, struct kvm_memory_slot *slot, > > + int level, unsigned int attr, > > + gfn_t start, gfn_t end) > > +{ > > + unsigned long gfn; > > + void *entry; > > + > > + if (level == PG_LEVEL_2M) > > + return mem_attr_is_mixed_2m(kvm, attr, start, end); > > + > > + entry = xa_load(&kvm->mem_attr_array, start); > > + for (gfn = start; gfn < end; gfn += KVM_PAGES_PER_HPAGE(level - 1)) { > > + if (linfo_is_mixed(lpage_info_slot(gfn, slot, level - 1))) > > + return true; > > + if (xa_load(&kvm->mem_attr_array, gfn) != entry) > > + return true; > > + } > > + return false; > > +} > > + > > +void kvm_arch_update_mem_attr(struct kvm *kvm, struct kvm_memory_slot *slot, > > + unsigned int attr, gfn_t start, gfn_t end) > > +{ > > + > > + unsigned long lpage_start, lpage_end; > > + unsigned long gfn, pages, mask; > > + int level; > > + > > + WARN_ONCE(!(attr & (KVM_MEM_ATTR_PRIVATE | KVM_MEM_ATTR_SHARED)), > > + "Unsupported mem attribute.\n"); > > + > > + /* > > + * The sequence matters here: we update the higher level basing on the > > + * lower level's scanning result. > > + */ > > + for (level = PG_LEVEL_2M; level <= KVM_MAX_HUGEPAGE_LEVEL; level++) { > > + pages = KVM_PAGES_PER_HPAGE(level); > > + mask = ~(pages - 1); > > nitpick: KVM_HPAGE_MASK(level). Maybe matter of preference. Yes, haven't noticed there is a KVM_HPAGE_MASK defined. Have no strong preference here, since I already have KVM_PAGES_PER_HPAGE(level), getting mask is straightforward. A single KVM_HPAGE_MASK(level) will not give me what I need since here is gfn, KVM_HPAGE_MASK(level)>> PAGE_SHIFT should be the right equivalent. Chao > > > > + lpage_start = max(start & mask, slot->base_gfn); > > + lpage_end = (end - 1) & mask; > > + > > + /* > > + * We only need to scan the head and tail page, for middle pages > > + * we know they are not mixed. > > + */ > > + linfo_update_mixed(lpage_info_slot(lpage_start, slot, level), > > + mem_attr_is_mixed(kvm, slot, level, attr, > > + lpage_start, start)); > > + > > + if (lpage_start == lpage_end) > > + return; > > + > > + for (gfn = lpage_start + pages; gfn < lpage_end; gfn += pages) > > + linfo_update_mixed(lpage_info_slot(gfn, slot, level), > > + false); > > + > > + linfo_update_mixed(lpage_info_slot(lpage_end, slot, level), > > + mem_attr_is_mixed(kvm, slot, level, attr, > > + end, lpage_end + pages)); > > + } > > +} > > -- > Isaku Yamahata <isaku.yamahata@gmail.com>
On Tue, Oct 25, 2022 at 11:13:42PM +0800, Chao Peng wrote: > When private/shared memory are mixed in a large page, the lpage_info may > not be accurate and should be updated with this mixed info. A large page > has mixed pages can't be really mapped as large page since its > private/shared pages are from different physical memory. > > Update lpage_info when private/shared memory attribute is changed. If > both private and shared pages are within a large page region, it can't > be mapped as large page. It's a bit challenge to track the mixed > info in a 'count' like variable, this patch instead reserves a bit in > 'disallow_lpage' to indicate a large page has mixed private/share pages. > > Signed-off-by: Chao Peng <chao.p.peng@linux.intel.com> > --- > arch/x86/include/asm/kvm_host.h | 8 +++ > arch/x86/kvm/mmu/mmu.c | 112 +++++++++++++++++++++++++++++++- > arch/x86/kvm/x86.c | 2 + > include/linux/kvm_host.h | 19 ++++++ > virt/kvm/kvm_main.c | 16 +++-- > 5 files changed, 152 insertions(+), 5 deletions(-) > > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h > index 7551b6f9c31c..db811a54e3fd 100644 > --- a/arch/x86/include/asm/kvm_host.h > +++ b/arch/x86/include/asm/kvm_host.h > @@ -37,6 +37,7 @@ > #include <asm/hyperv-tlfs.h> > > #define __KVM_HAVE_ARCH_VCPU_DEBUGFS > +#define __KVM_HAVE_ARCH_UPDATE_MEM_ATTR > > #define KVM_MAX_VCPUS 1024 > > @@ -952,6 +953,13 @@ struct kvm_vcpu_arch { > #endif > }; > > +/* > + * Use a bit in disallow_lpage to indicate private/shared pages mixed at the > + * level. The remaining bits are used as a reference count. > + */ > +#define KVM_LPAGE_PRIVATE_SHARED_MIXED (1U << 31) > +#define KVM_LPAGE_COUNT_MAX ((1U << 31) - 1) > + > struct kvm_lpage_info { > int disallow_lpage; > }; > diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c > index 33b1aec44fb8..67a9823a8c35 100644 > --- a/arch/x86/kvm/mmu/mmu.c > +++ b/arch/x86/kvm/mmu/mmu.c > @@ -762,11 +762,16 @@ static void update_gfn_disallow_lpage_count(const struct kvm_memory_slot *slot, > { > struct kvm_lpage_info *linfo; > int i; > + int disallow_count; > > for (i = PG_LEVEL_2M; i <= KVM_MAX_HUGEPAGE_LEVEL; ++i) { > linfo = lpage_info_slot(gfn, slot, i); > + > + disallow_count = linfo->disallow_lpage & KVM_LPAGE_COUNT_MAX; > + WARN_ON(disallow_count + count < 0 || > + disallow_count > KVM_LPAGE_COUNT_MAX - count); > + > linfo->disallow_lpage += count; > - WARN_ON(linfo->disallow_lpage < 0); > } > } > > @@ -6910,3 +6915,108 @@ void kvm_mmu_pre_destroy_vm(struct kvm *kvm) > if (kvm->arch.nx_lpage_recovery_thread) > kthread_stop(kvm->arch.nx_lpage_recovery_thread); > } > + > +static inline bool linfo_is_mixed(struct kvm_lpage_info *linfo) > +{ > + return linfo->disallow_lpage & KVM_LPAGE_PRIVATE_SHARED_MIXED; > +} > + > +static inline void linfo_update_mixed(struct kvm_lpage_info *linfo, bool mixed) > +{ > + if (mixed) > + linfo->disallow_lpage |= KVM_LPAGE_PRIVATE_SHARED_MIXED; > + else > + linfo->disallow_lpage &= ~KVM_LPAGE_PRIVATE_SHARED_MIXED; > +} > + > +static bool mem_attr_is_mixed_2m(struct kvm *kvm, unsigned int attr, > + gfn_t start, gfn_t end) > +{ > + XA_STATE(xas, &kvm->mem_attr_array, start); > + gfn_t gfn = start; > + void *entry; > + bool shared = attr == KVM_MEM_ATTR_SHARED; > + bool mixed = false; > + > + rcu_read_lock(); > + entry = xas_load(&xas); > + while (gfn < end) { > + if (xas_retry(&xas, entry)) > + continue; > + > + KVM_BUG_ON(gfn != xas.xa_index, kvm); > + > + if ((entry && !shared) || (!entry && shared)) { > + mixed = true; > + goto out; > + } > + > + entry = xas_next(&xas); > + gfn++; > + } > +out: > + rcu_read_unlock(); > + return mixed; > +} > + > +static bool mem_attr_is_mixed(struct kvm *kvm, struct kvm_memory_slot *slot, > + int level, unsigned int attr, > + gfn_t start, gfn_t end) > +{ > + unsigned long gfn; > + void *entry; > + > + if (level == PG_LEVEL_2M) > + return mem_attr_is_mixed_2m(kvm, attr, start, end); > + > + entry = xa_load(&kvm->mem_attr_array, start); > + for (gfn = start; gfn < end; gfn += KVM_PAGES_PER_HPAGE(level - 1)) { > + if (linfo_is_mixed(lpage_info_slot(gfn, slot, level - 1))) > + return true; > + if (xa_load(&kvm->mem_attr_array, gfn) != entry) > + return true; > + } > + return false; > +} > + > +void kvm_arch_update_mem_attr(struct kvm *kvm, struct kvm_memory_slot *slot, > + unsigned int attr, gfn_t start, gfn_t end) > +{ > + > + unsigned long lpage_start, lpage_end; > + unsigned long gfn, pages, mask; > + int level; > + > + WARN_ONCE(!(attr & (KVM_MEM_ATTR_PRIVATE | KVM_MEM_ATTR_SHARED)), > + "Unsupported mem attribute.\n"); > + > + /* > + * The sequence matters here: we update the higher level basing on the > + * lower level's scanning result. > + */ > + for (level = PG_LEVEL_2M; level <= KVM_MAX_HUGEPAGE_LEVEL; level++) { > + pages = KVM_PAGES_PER_HPAGE(level); > + mask = ~(pages - 1); > + lpage_start = max(start & mask, slot->base_gfn); > + lpage_end = (end - 1) & mask; > + > + /* > + * We only need to scan the head and tail page, for middle pages > + * we know they are not mixed. > + */ > + linfo_update_mixed(lpage_info_slot(lpage_start, slot, level), > + mem_attr_is_mixed(kvm, slot, level, attr, > + lpage_start, start)); Looks only query the lpage_start, start is not enough: A and B are private gfns from same lpage_start as below, A > B : lpage_start |---------A |----B Convert A to shared, this makes the upper 2M page to MIX. Convert B to shared, this also makes the upper 2M page to MIX. Convert B to private, this makes the upper 2M page to Non-MIX, but it's incorrect, due to A is shared. Same to tail case. > + > + if (lpage_start == lpage_end) > + return; > + > + for (gfn = lpage_start + pages; gfn < lpage_end; gfn += pages) > + linfo_update_mixed(lpage_info_slot(gfn, slot, level), > + false); > + > + linfo_update_mixed(lpage_info_slot(lpage_end, slot, level), > + mem_attr_is_mixed(kvm, slot, level, attr, > + end, lpage_end + pages)); > + } > +} > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 02ad31f46dd7..4276ca73bd7b 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -12563,6 +12563,8 @@ static int kvm_alloc_memslot_metadata(struct kvm *kvm, > if ((slot->base_gfn + npages) & (KVM_PAGES_PER_HPAGE(level) - 1)) > linfo[lpages - 1].disallow_lpage = 1; > ugfn = slot->userspace_addr >> PAGE_SHIFT; > + if (kvm_slot_can_be_private(slot)) > + ugfn |= slot->restricted_offset >> PAGE_SHIFT; > /* > * If the gfn and userspace address are not aligned wrt each > * other, disable large page support for this slot. > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h > index 4ce98fa0153c..6ce36065532c 100644 > --- a/include/linux/kvm_host.h > +++ b/include/linux/kvm_host.h > @@ -2284,4 +2284,23 @@ static inline void kvm_account_pgtable_pages(void *virt, int nr) > /* Max number of entries allowed for each kvm dirty ring */ > #define KVM_DIRTY_RING_MAX_ENTRIES 65536 > > +#ifdef CONFIG_KVM_GENERIC_PRIVATE_MEM > + > +#define KVM_MEM_ATTR_SHARED 0x0001 > +#define KVM_MEM_ATTR_PRIVATE 0x0002 > + > +#ifdef __KVM_HAVE_ARCH_UPDATE_MEM_ATTR > +void kvm_arch_update_mem_attr(struct kvm *kvm, struct kvm_memory_slot *slot, > + unsigned int attr, gfn_t start, gfn_t end); > +#else > +static inline void kvm_arch_update_mem_attr(struct kvm *kvm, > + struct kvm_memory_slot *slot, > + unsigned int attr, > + gfn_t start, gfn_t end) > +{ > +} > +#endif > + > +#endif /* CONFIG_KVM_GENERIC_PRIVATE_MEM */ > + > #endif > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > index fc3835826ace..13a37b4d9e97 100644 > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -939,7 +939,8 @@ static int kvm_init_mmu_notifier(struct kvm *kvm) > > #ifdef CONFIG_KVM_GENERIC_PRIVATE_MEM > > -static void kvm_unmap_mem_range(struct kvm *kvm, gfn_t start, gfn_t end) > +static void kvm_unmap_mem_range(struct kvm *kvm, gfn_t start, gfn_t end, > + unsigned int attr) > { > struct kvm_gfn_range gfn_range; > struct kvm_memory_slot *slot; > @@ -963,6 +964,7 @@ static void kvm_unmap_mem_range(struct kvm *kvm, gfn_t start, gfn_t end) > gfn_range.slot = slot; > > r |= kvm_unmap_gfn_range(kvm, &gfn_range); > + kvm_arch_update_mem_attr(kvm, slot, attr, start, end); > } > } > > @@ -970,7 +972,6 @@ static void kvm_unmap_mem_range(struct kvm *kvm, gfn_t start, gfn_t end) > kvm_flush_remote_tlbs(kvm); > } > > -#define KVM_MEM_ATTR_SHARED 0x0001 > static int kvm_vm_ioctl_set_mem_attr(struct kvm *kvm, gpa_t gpa, gpa_t size, > bool is_private) > { > @@ -979,6 +980,7 @@ static int kvm_vm_ioctl_set_mem_attr(struct kvm *kvm, gpa_t gpa, gpa_t size, > void *entry; > int idx; > int r = 0; > + unsigned int attr; > > if (size == 0 || gpa + size < gpa) > return -EINVAL; > @@ -992,7 +994,13 @@ static int kvm_vm_ioctl_set_mem_attr(struct kvm *kvm, gpa_t gpa, gpa_t size, > * Guest memory defaults to private, kvm->mem_attr_array only stores > * shared memory. > */ > - entry = is_private ? NULL : xa_mk_value(KVM_MEM_ATTR_SHARED); > + if (is_private) { > + attr = KVM_MEM_ATTR_PRIVATE; > + entry = NULL; > + } else { > + attr = KVM_MEM_ATTR_SHARED; > + entry = xa_mk_value(KVM_MEM_ATTR_SHARED); > + } > > idx = srcu_read_lock(&kvm->srcu); > KVM_MMU_LOCK(kvm); > @@ -1005,7 +1013,7 @@ static int kvm_vm_ioctl_set_mem_attr(struct kvm *kvm, gpa_t gpa, gpa_t size, > goto err; > } > > - kvm_unmap_mem_range(kvm, start, end); > + kvm_unmap_mem_range(kvm, start, end, attr); > > goto ret; > err: > -- > 2.25.1 >
On Tue, Nov 08, 2022 at 08:08:05PM +0800, Yuan Yao wrote: > On Tue, Oct 25, 2022 at 11:13:42PM +0800, Chao Peng wrote: > > When private/shared memory are mixed in a large page, the lpage_info may > > not be accurate and should be updated with this mixed info. A large page > > has mixed pages can't be really mapped as large page since its > > private/shared pages are from different physical memory. > > > > Update lpage_info when private/shared memory attribute is changed. If > > both private and shared pages are within a large page region, it can't > > be mapped as large page. It's a bit challenge to track the mixed > > info in a 'count' like variable, this patch instead reserves a bit in > > 'disallow_lpage' to indicate a large page has mixed private/share pages. > > > > Signed-off-by: Chao Peng <chao.p.peng@linux.intel.com> > > --- > > arch/x86/include/asm/kvm_host.h | 8 +++ > > arch/x86/kvm/mmu/mmu.c | 112 +++++++++++++++++++++++++++++++- > > arch/x86/kvm/x86.c | 2 + > > include/linux/kvm_host.h | 19 ++++++ > > virt/kvm/kvm_main.c | 16 +++-- > > 5 files changed, 152 insertions(+), 5 deletions(-) > > > > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h > > index 7551b6f9c31c..db811a54e3fd 100644 > > --- a/arch/x86/include/asm/kvm_host.h > > +++ b/arch/x86/include/asm/kvm_host.h > > @@ -37,6 +37,7 @@ > > #include <asm/hyperv-tlfs.h> > > > > #define __KVM_HAVE_ARCH_VCPU_DEBUGFS > > +#define __KVM_HAVE_ARCH_UPDATE_MEM_ATTR > > > > #define KVM_MAX_VCPUS 1024 > > > > @@ -952,6 +953,13 @@ struct kvm_vcpu_arch { > > #endif > > }; > > > > +/* > > + * Use a bit in disallow_lpage to indicate private/shared pages mixed at the > > + * level. The remaining bits are used as a reference count. > > + */ > > +#define KVM_LPAGE_PRIVATE_SHARED_MIXED (1U << 31) > > +#define KVM_LPAGE_COUNT_MAX ((1U << 31) - 1) > > + > > struct kvm_lpage_info { > > int disallow_lpage; > > }; > > diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c > > index 33b1aec44fb8..67a9823a8c35 100644 > > --- a/arch/x86/kvm/mmu/mmu.c > > +++ b/arch/x86/kvm/mmu/mmu.c > > @@ -762,11 +762,16 @@ static void update_gfn_disallow_lpage_count(const struct kvm_memory_slot *slot, > > { > > struct kvm_lpage_info *linfo; > > int i; > > + int disallow_count; > > > > for (i = PG_LEVEL_2M; i <= KVM_MAX_HUGEPAGE_LEVEL; ++i) { > > linfo = lpage_info_slot(gfn, slot, i); > > + > > + disallow_count = linfo->disallow_lpage & KVM_LPAGE_COUNT_MAX; > > + WARN_ON(disallow_count + count < 0 || > > + disallow_count > KVM_LPAGE_COUNT_MAX - count); > > + > > linfo->disallow_lpage += count; > > - WARN_ON(linfo->disallow_lpage < 0); > > } > > } > > > > @@ -6910,3 +6915,108 @@ void kvm_mmu_pre_destroy_vm(struct kvm *kvm) > > if (kvm->arch.nx_lpage_recovery_thread) > > kthread_stop(kvm->arch.nx_lpage_recovery_thread); > > } > > + > > +static inline bool linfo_is_mixed(struct kvm_lpage_info *linfo) > > +{ > > + return linfo->disallow_lpage & KVM_LPAGE_PRIVATE_SHARED_MIXED; > > +} > > + > > +static inline void linfo_update_mixed(struct kvm_lpage_info *linfo, bool mixed) > > +{ > > + if (mixed) > > + linfo->disallow_lpage |= KVM_LPAGE_PRIVATE_SHARED_MIXED; > > + else > > + linfo->disallow_lpage &= ~KVM_LPAGE_PRIVATE_SHARED_MIXED; > > +} > > + > > +static bool mem_attr_is_mixed_2m(struct kvm *kvm, unsigned int attr, > > + gfn_t start, gfn_t end) > > +{ > > + XA_STATE(xas, &kvm->mem_attr_array, start); > > + gfn_t gfn = start; > > + void *entry; > > + bool shared = attr == KVM_MEM_ATTR_SHARED; > > + bool mixed = false; > > + > > + rcu_read_lock(); > > + entry = xas_load(&xas); > > + while (gfn < end) { > > + if (xas_retry(&xas, entry)) > > + continue; > > + > > + KVM_BUG_ON(gfn != xas.xa_index, kvm); > > + > > + if ((entry && !shared) || (!entry && shared)) { > > + mixed = true; > > + goto out; > > + } > > + > > + entry = xas_next(&xas); > > + gfn++; > > + } > > +out: > > + rcu_read_unlock(); > > + return mixed; > > +} > > + > > +static bool mem_attr_is_mixed(struct kvm *kvm, struct kvm_memory_slot *slot, > > + int level, unsigned int attr, > > + gfn_t start, gfn_t end) > > +{ > > + unsigned long gfn; > > + void *entry; > > + > > + if (level == PG_LEVEL_2M) > > + return mem_attr_is_mixed_2m(kvm, attr, start, end); > > + > > + entry = xa_load(&kvm->mem_attr_array, start); > > + for (gfn = start; gfn < end; gfn += KVM_PAGES_PER_HPAGE(level - 1)) { > > + if (linfo_is_mixed(lpage_info_slot(gfn, slot, level - 1))) > > + return true; > > + if (xa_load(&kvm->mem_attr_array, gfn) != entry) > > + return true; > > + } > > + return false; > > +} > > + > > +void kvm_arch_update_mem_attr(struct kvm *kvm, struct kvm_memory_slot *slot, > > + unsigned int attr, gfn_t start, gfn_t end) > > +{ > > + > > + unsigned long lpage_start, lpage_end; > > + unsigned long gfn, pages, mask; > > + int level; > > + > > + WARN_ONCE(!(attr & (KVM_MEM_ATTR_PRIVATE | KVM_MEM_ATTR_SHARED)), > > + "Unsupported mem attribute.\n"); > > + > > + /* > > + * The sequence matters here: we update the higher level basing on the > > + * lower level's scanning result. > > + */ > > + for (level = PG_LEVEL_2M; level <= KVM_MAX_HUGEPAGE_LEVEL; level++) { > > + pages = KVM_PAGES_PER_HPAGE(level); > > + mask = ~(pages - 1); > > + lpage_start = max(start & mask, slot->base_gfn); > > + lpage_end = (end - 1) & mask; > > + > > + /* > > + * We only need to scan the head and tail page, for middle pages > > + * we know they are not mixed. > > + */ > > + linfo_update_mixed(lpage_info_slot(lpage_start, slot, level), > > + mem_attr_is_mixed(kvm, slot, level, attr, > > + lpage_start, start)); > > Looks only query the lpage_start, start is not enough: > > A and B are private gfns from same lpage_start as below, A > B : > lpage_start > |---------A > |----B > > Convert A to shared, this makes the upper 2M page to MIX. > Convert B to shared, this also makes the upper 2M page to MIX. > Convert B to private, this makes the upper 2M page to Non-MIX, but > it's incorrect, due to A is shared. In previous versions this is actually "lpage_start, lpage_start + pages", e.g. covers the whole large page. While fixing another issue[*] in v8 this was wrongly changed to "lpage_start, start", at that time I made an assumption that "end > lpage_start + pages" so the remaining scanning in the same large page is useless if we know what attribute we will set, this is definitely not true though. [*] https://lore.kernel.org/linux-mm/20220930085914.GA2799703@chaop.bj.intel.com/ Thanks, Chao > > Same to tail case. > > > + > > + if (lpage_start == lpage_end) > > + return; > > + > > + for (gfn = lpage_start + pages; gfn < lpage_end; gfn += pages) > > + linfo_update_mixed(lpage_info_slot(gfn, slot, level), > > + false); > > + > > + linfo_update_mixed(lpage_info_slot(lpage_end, slot, level), > > + mem_attr_is_mixed(kvm, slot, level, attr, > > + end, lpage_end + pages)); > > + } > > +} > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > > index 02ad31f46dd7..4276ca73bd7b 100644 > > --- a/arch/x86/kvm/x86.c > > +++ b/arch/x86/kvm/x86.c > > @@ -12563,6 +12563,8 @@ static int kvm_alloc_memslot_metadata(struct kvm *kvm, > > if ((slot->base_gfn + npages) & (KVM_PAGES_PER_HPAGE(level) - 1)) > > linfo[lpages - 1].disallow_lpage = 1; > > ugfn = slot->userspace_addr >> PAGE_SHIFT; > > + if (kvm_slot_can_be_private(slot)) > > + ugfn |= slot->restricted_offset >> PAGE_SHIFT; > > /* > > * If the gfn and userspace address are not aligned wrt each > > * other, disable large page support for this slot. > > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h > > index 4ce98fa0153c..6ce36065532c 100644 > > --- a/include/linux/kvm_host.h > > +++ b/include/linux/kvm_host.h > > @@ -2284,4 +2284,23 @@ static inline void kvm_account_pgtable_pages(void *virt, int nr) > > /* Max number of entries allowed for each kvm dirty ring */ > > #define KVM_DIRTY_RING_MAX_ENTRIES 65536 > > > > +#ifdef CONFIG_KVM_GENERIC_PRIVATE_MEM > > + > > +#define KVM_MEM_ATTR_SHARED 0x0001 > > +#define KVM_MEM_ATTR_PRIVATE 0x0002 > > + > > +#ifdef __KVM_HAVE_ARCH_UPDATE_MEM_ATTR > > +void kvm_arch_update_mem_attr(struct kvm *kvm, struct kvm_memory_slot *slot, > > + unsigned int attr, gfn_t start, gfn_t end); > > +#else > > +static inline void kvm_arch_update_mem_attr(struct kvm *kvm, > > + struct kvm_memory_slot *slot, > > + unsigned int attr, > > + gfn_t start, gfn_t end) > > +{ > > +} > > +#endif > > + > > +#endif /* CONFIG_KVM_GENERIC_PRIVATE_MEM */ > > + > > #endif > > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > > index fc3835826ace..13a37b4d9e97 100644 > > --- a/virt/kvm/kvm_main.c > > +++ b/virt/kvm/kvm_main.c > > @@ -939,7 +939,8 @@ static int kvm_init_mmu_notifier(struct kvm *kvm) > > > > #ifdef CONFIG_KVM_GENERIC_PRIVATE_MEM > > > > -static void kvm_unmap_mem_range(struct kvm *kvm, gfn_t start, gfn_t end) > > +static void kvm_unmap_mem_range(struct kvm *kvm, gfn_t start, gfn_t end, > > + unsigned int attr) > > { > > struct kvm_gfn_range gfn_range; > > struct kvm_memory_slot *slot; > > @@ -963,6 +964,7 @@ static void kvm_unmap_mem_range(struct kvm *kvm, gfn_t start, gfn_t end) > > gfn_range.slot = slot; > > > > r |= kvm_unmap_gfn_range(kvm, &gfn_range); > > + kvm_arch_update_mem_attr(kvm, slot, attr, start, end); > > } > > } > > > > @@ -970,7 +972,6 @@ static void kvm_unmap_mem_range(struct kvm *kvm, gfn_t start, gfn_t end) > > kvm_flush_remote_tlbs(kvm); > > } > > > > -#define KVM_MEM_ATTR_SHARED 0x0001 > > static int kvm_vm_ioctl_set_mem_attr(struct kvm *kvm, gpa_t gpa, gpa_t size, > > bool is_private) > > { > > @@ -979,6 +980,7 @@ static int kvm_vm_ioctl_set_mem_attr(struct kvm *kvm, gpa_t gpa, gpa_t size, > > void *entry; > > int idx; > > int r = 0; > > + unsigned int attr; > > > > if (size == 0 || gpa + size < gpa) > > return -EINVAL; > > @@ -992,7 +994,13 @@ static int kvm_vm_ioctl_set_mem_attr(struct kvm *kvm, gpa_t gpa, gpa_t size, > > * Guest memory defaults to private, kvm->mem_attr_array only stores > > * shared memory. > > */ > > - entry = is_private ? NULL : xa_mk_value(KVM_MEM_ATTR_SHARED); > > + if (is_private) { > > + attr = KVM_MEM_ATTR_PRIVATE; > > + entry = NULL; > > + } else { > > + attr = KVM_MEM_ATTR_SHARED; > > + entry = xa_mk_value(KVM_MEM_ATTR_SHARED); > > + } > > > > idx = srcu_read_lock(&kvm->srcu); > > KVM_MMU_LOCK(kvm); > > @@ -1005,7 +1013,7 @@ static int kvm_vm_ioctl_set_mem_attr(struct kvm *kvm, gpa_t gpa, gpa_t size, > > goto err; > > } > > > > - kvm_unmap_mem_range(kvm, start, end); > > + kvm_unmap_mem_range(kvm, start, end, attr); > > > > goto ret; > > err: > > -- > > 2.25.1 > >
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 7551b6f9c31c..db811a54e3fd 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -37,6 +37,7 @@ #include <asm/hyperv-tlfs.h> #define __KVM_HAVE_ARCH_VCPU_DEBUGFS +#define __KVM_HAVE_ARCH_UPDATE_MEM_ATTR #define KVM_MAX_VCPUS 1024 @@ -952,6 +953,13 @@ struct kvm_vcpu_arch { #endif }; +/* + * Use a bit in disallow_lpage to indicate private/shared pages mixed at the + * level. The remaining bits are used as a reference count. + */ +#define KVM_LPAGE_PRIVATE_SHARED_MIXED (1U << 31) +#define KVM_LPAGE_COUNT_MAX ((1U << 31) - 1) + struct kvm_lpage_info { int disallow_lpage; }; diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 33b1aec44fb8..67a9823a8c35 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -762,11 +762,16 @@ static void update_gfn_disallow_lpage_count(const struct kvm_memory_slot *slot, { struct kvm_lpage_info *linfo; int i; + int disallow_count; for (i = PG_LEVEL_2M; i <= KVM_MAX_HUGEPAGE_LEVEL; ++i) { linfo = lpage_info_slot(gfn, slot, i); + + disallow_count = linfo->disallow_lpage & KVM_LPAGE_COUNT_MAX; + WARN_ON(disallow_count + count < 0 || + disallow_count > KVM_LPAGE_COUNT_MAX - count); + linfo->disallow_lpage += count; - WARN_ON(linfo->disallow_lpage < 0); } } @@ -6910,3 +6915,108 @@ void kvm_mmu_pre_destroy_vm(struct kvm *kvm) if (kvm->arch.nx_lpage_recovery_thread) kthread_stop(kvm->arch.nx_lpage_recovery_thread); } + +static inline bool linfo_is_mixed(struct kvm_lpage_info *linfo) +{ + return linfo->disallow_lpage & KVM_LPAGE_PRIVATE_SHARED_MIXED; +} + +static inline void linfo_update_mixed(struct kvm_lpage_info *linfo, bool mixed) +{ + if (mixed) + linfo->disallow_lpage |= KVM_LPAGE_PRIVATE_SHARED_MIXED; + else + linfo->disallow_lpage &= ~KVM_LPAGE_PRIVATE_SHARED_MIXED; +} + +static bool mem_attr_is_mixed_2m(struct kvm *kvm, unsigned int attr, + gfn_t start, gfn_t end) +{ + XA_STATE(xas, &kvm->mem_attr_array, start); + gfn_t gfn = start; + void *entry; + bool shared = attr == KVM_MEM_ATTR_SHARED; + bool mixed = false; + + rcu_read_lock(); + entry = xas_load(&xas); + while (gfn < end) { + if (xas_retry(&xas, entry)) + continue; + + KVM_BUG_ON(gfn != xas.xa_index, kvm); + + if ((entry && !shared) || (!entry && shared)) { + mixed = true; + goto out; + } + + entry = xas_next(&xas); + gfn++; + } +out: + rcu_read_unlock(); + return mixed; +} + +static bool mem_attr_is_mixed(struct kvm *kvm, struct kvm_memory_slot *slot, + int level, unsigned int attr, + gfn_t start, gfn_t end) +{ + unsigned long gfn; + void *entry; + + if (level == PG_LEVEL_2M) + return mem_attr_is_mixed_2m(kvm, attr, start, end); + + entry = xa_load(&kvm->mem_attr_array, start); + for (gfn = start; gfn < end; gfn += KVM_PAGES_PER_HPAGE(level - 1)) { + if (linfo_is_mixed(lpage_info_slot(gfn, slot, level - 1))) + return true; + if (xa_load(&kvm->mem_attr_array, gfn) != entry) + return true; + } + return false; +} + +void kvm_arch_update_mem_attr(struct kvm *kvm, struct kvm_memory_slot *slot, + unsigned int attr, gfn_t start, gfn_t end) +{ + + unsigned long lpage_start, lpage_end; + unsigned long gfn, pages, mask; + int level; + + WARN_ONCE(!(attr & (KVM_MEM_ATTR_PRIVATE | KVM_MEM_ATTR_SHARED)), + "Unsupported mem attribute.\n"); + + /* + * The sequence matters here: we update the higher level basing on the + * lower level's scanning result. + */ + for (level = PG_LEVEL_2M; level <= KVM_MAX_HUGEPAGE_LEVEL; level++) { + pages = KVM_PAGES_PER_HPAGE(level); + mask = ~(pages - 1); + lpage_start = max(start & mask, slot->base_gfn); + lpage_end = (end - 1) & mask; + + /* + * We only need to scan the head and tail page, for middle pages + * we know they are not mixed. + */ + linfo_update_mixed(lpage_info_slot(lpage_start, slot, level), + mem_attr_is_mixed(kvm, slot, level, attr, + lpage_start, start)); + + if (lpage_start == lpage_end) + return; + + for (gfn = lpage_start + pages; gfn < lpage_end; gfn += pages) + linfo_update_mixed(lpage_info_slot(gfn, slot, level), + false); + + linfo_update_mixed(lpage_info_slot(lpage_end, slot, level), + mem_attr_is_mixed(kvm, slot, level, attr, + end, lpage_end + pages)); + } +} diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 02ad31f46dd7..4276ca73bd7b 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -12563,6 +12563,8 @@ static int kvm_alloc_memslot_metadata(struct kvm *kvm, if ((slot->base_gfn + npages) & (KVM_PAGES_PER_HPAGE(level) - 1)) linfo[lpages - 1].disallow_lpage = 1; ugfn = slot->userspace_addr >> PAGE_SHIFT; + if (kvm_slot_can_be_private(slot)) + ugfn |= slot->restricted_offset >> PAGE_SHIFT; /* * If the gfn and userspace address are not aligned wrt each * other, disable large page support for this slot. diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 4ce98fa0153c..6ce36065532c 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -2284,4 +2284,23 @@ static inline void kvm_account_pgtable_pages(void *virt, int nr) /* Max number of entries allowed for each kvm dirty ring */ #define KVM_DIRTY_RING_MAX_ENTRIES 65536 +#ifdef CONFIG_KVM_GENERIC_PRIVATE_MEM + +#define KVM_MEM_ATTR_SHARED 0x0001 +#define KVM_MEM_ATTR_PRIVATE 0x0002 + +#ifdef __KVM_HAVE_ARCH_UPDATE_MEM_ATTR +void kvm_arch_update_mem_attr(struct kvm *kvm, struct kvm_memory_slot *slot, + unsigned int attr, gfn_t start, gfn_t end); +#else +static inline void kvm_arch_update_mem_attr(struct kvm *kvm, + struct kvm_memory_slot *slot, + unsigned int attr, + gfn_t start, gfn_t end) +{ +} +#endif + +#endif /* CONFIG_KVM_GENERIC_PRIVATE_MEM */ + #endif diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index fc3835826ace..13a37b4d9e97 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -939,7 +939,8 @@ static int kvm_init_mmu_notifier(struct kvm *kvm) #ifdef CONFIG_KVM_GENERIC_PRIVATE_MEM -static void kvm_unmap_mem_range(struct kvm *kvm, gfn_t start, gfn_t end) +static void kvm_unmap_mem_range(struct kvm *kvm, gfn_t start, gfn_t end, + unsigned int attr) { struct kvm_gfn_range gfn_range; struct kvm_memory_slot *slot; @@ -963,6 +964,7 @@ static void kvm_unmap_mem_range(struct kvm *kvm, gfn_t start, gfn_t end) gfn_range.slot = slot; r |= kvm_unmap_gfn_range(kvm, &gfn_range); + kvm_arch_update_mem_attr(kvm, slot, attr, start, end); } } @@ -970,7 +972,6 @@ static void kvm_unmap_mem_range(struct kvm *kvm, gfn_t start, gfn_t end) kvm_flush_remote_tlbs(kvm); } -#define KVM_MEM_ATTR_SHARED 0x0001 static int kvm_vm_ioctl_set_mem_attr(struct kvm *kvm, gpa_t gpa, gpa_t size, bool is_private) { @@ -979,6 +980,7 @@ static int kvm_vm_ioctl_set_mem_attr(struct kvm *kvm, gpa_t gpa, gpa_t size, void *entry; int idx; int r = 0; + unsigned int attr; if (size == 0 || gpa + size < gpa) return -EINVAL; @@ -992,7 +994,13 @@ static int kvm_vm_ioctl_set_mem_attr(struct kvm *kvm, gpa_t gpa, gpa_t size, * Guest memory defaults to private, kvm->mem_attr_array only stores * shared memory. */ - entry = is_private ? NULL : xa_mk_value(KVM_MEM_ATTR_SHARED); + if (is_private) { + attr = KVM_MEM_ATTR_PRIVATE; + entry = NULL; + } else { + attr = KVM_MEM_ATTR_SHARED; + entry = xa_mk_value(KVM_MEM_ATTR_SHARED); + } idx = srcu_read_lock(&kvm->srcu); KVM_MMU_LOCK(kvm); @@ -1005,7 +1013,7 @@ static int kvm_vm_ioctl_set_mem_attr(struct kvm *kvm, gpa_t gpa, gpa_t size, goto err; } - kvm_unmap_mem_range(kvm, start, end); + kvm_unmap_mem_range(kvm, start, end, attr); goto ret; err:
When private/shared memory are mixed in a large page, the lpage_info may not be accurate and should be updated with this mixed info. A large page has mixed pages can't be really mapped as large page since its private/shared pages are from different physical memory. Update lpage_info when private/shared memory attribute is changed. If both private and shared pages are within a large page region, it can't be mapped as large page. It's a bit challenge to track the mixed info in a 'count' like variable, this patch instead reserves a bit in 'disallow_lpage' to indicate a large page has mixed private/share pages. Signed-off-by: Chao Peng <chao.p.peng@linux.intel.com> --- arch/x86/include/asm/kvm_host.h | 8 +++ arch/x86/kvm/mmu/mmu.c | 112 +++++++++++++++++++++++++++++++- arch/x86/kvm/x86.c | 2 + include/linux/kvm_host.h | 19 ++++++ virt/kvm/kvm_main.c | 16 +++-- 5 files changed, 152 insertions(+), 5 deletions(-)