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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [RFC v2 5/6] xen/arm: Implement hypercall for dirty page tracing
From: Jaeyong Yoo <jaeyong.yoo@xxxxxxxxxxx>
This patch adds hypercall for shadow operations, including enable/disable
and clean/peek dirty page bitmap.
The design consists of two parts: dirty page detecting and saving. For
detecting, we setup the guest p2m's leaf PTE read-only and whenever
the guest tries to write something, permission fault happens and traps
into xen. The permission-faulted GPA should be saved for the toolstack,
which checks which pages are dirty. For this purpose, it temporarily saves
the GPAs into bitmap.
Signed-off-by: Jaeyong Yoo <jaeyong.yoo@xxxxxxxxxxx>
Signed-off-by: Wei Huang <w1.huang@xxxxxxxxxxx>
---
xen/arch/arm/domain.c | 14 +++
xen/arch/arm/domctl.c | 21 ++++
xen/arch/arm/mm.c | 105 ++++++++++++++++++-
xen/arch/arm/p2m.c | 211 +++++++++++++++++++++++++++++++++++++++
xen/arch/arm/traps.c | 11 ++
xen/include/asm-arm/domain.h | 7 ++
xen/include/asm-arm/mm.h | 10 ++
xen/include/asm-arm/p2m.h | 8 +-
xen/include/asm-arm/processor.h | 2 +
9 files changed, 387 insertions(+), 2 deletions(-)
diff --git a/xen/arch/arm/domain.c b/xen/arch/arm/domain.c
index 3f04a77..d2531ed 100644
--- a/xen/arch/arm/domain.c
+++ b/xen/arch/arm/domain.c
@@ -207,6 +207,12 @@ static void ctxt_switch_to(struct vcpu *n)
isb();
+ /* Dirty-page tracing
+ * NB: How do we consider SMP case?
+ */
+ if ( n->domain->arch.dirty.mode )
+ restore_vlpt(n->domain);
+
/* This is could trigger an hardware interrupt from the virtual
* timer. The interrupt needs to be injected into the guest. */
virt_timer_restore(n);
@@ -502,11 +508,19 @@ int arch_domain_create(struct domain *d, unsigned int
domcr_flags)
/* Default the virtual ID to match the physical */
d->arch.vpidr = boot_cpu_data.midr.bits;
+ /* init for dirty-page tracing */
+ d->arch.dirty.count = 0;
+ d->arch.dirty.mode = 0;
+ spin_lock_init(&d->arch.dirty.lock);
+
d->arch.dirty.second_lvl_start = 0;
d->arch.dirty.second_lvl_end = 0;
d->arch.dirty.second_lvl[0] = NULL;
d->arch.dirty.second_lvl[1] = NULL;
+ memset(d->arch.dirty.bitmap, 0, sizeof(d->arch.dirty.bitmap));
+ d->arch.dirty.bitmap_pages = 0;
+
clear_page(d->shared_info);
share_xen_page_with_guest(
virt_to_page(d->shared_info), d, XENSHARE_writable);
diff --git a/xen/arch/arm/domctl.c b/xen/arch/arm/domctl.c
index 45974e7..e84651f 100644
--- a/xen/arch/arm/domctl.c
+++ b/xen/arch/arm/domctl.c
@@ -11,12 +11,33 @@
#include <xen/sched.h>
#include <xen/hypercall.h>
#include <public/domctl.h>
+#include <xen/hvm/save.h>
+#include <xen/guest_access.h>
+
long arch_do_domctl(struct xen_domctl *domctl, struct domain *d,
XEN_GUEST_HANDLE_PARAM(xen_domctl_t) u_domctl)
{
+ long ret = 0;
+
switch ( domctl->cmd )
{
+ case XEN_DOMCTL_shadow_op:
+ {
+ if ( d == current->domain ) /* no domain_pause() */
+ return -EINVAL;
+
+ domain_pause(d);
+ ret = dirty_mode_op(d, &domctl->u.shadow_op);
+ domain_unpause(d);
+
+ if ( __copy_to_guest(u_domctl, domctl, 1) )
+ ret = -EFAULT;
+
+ return ret;
+ }
+ break;
+
case XEN_DOMCTL_cacheflush:
{
unsigned long s = domctl->u.cacheflush.start_pfn;
diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c
index a315752..ae852eb 100644
--- a/xen/arch/arm/mm.c
+++ b/xen/arch/arm/mm.c
@@ -981,7 +981,6 @@ void destroy_xen_mappings(unsigned long v, unsigned long e)
create_xen_entries(REMOVE, v, 0, (e - v) >> PAGE_SHIFT, 0);
}
-enum mg { mg_clear, mg_ro, mg_rw, mg_rx };
static void set_pte_flags_on_range(const char *p, unsigned long l, enum mg mg)
{
lpae_t pte;
@@ -1370,6 +1369,110 @@ void domain_get_gpfn_range(struct domain *d, paddr_t
*start, paddr_t *end)
*end = GUEST_RAM_BASE + ((paddr_t) p2m->max_mapped_gfn);
}
+static inline void mark_dirty_bitmap(struct domain *d, paddr_t addr)
+{
+ paddr_t ram_base = (paddr_t) GUEST_RAM_BASE;
+ int bit_index = PFN_DOWN(addr - ram_base);
+ int page_index = bit_index >> (PAGE_SHIFT + 3);
+ int bit_index_residual = bit_index & ((1ul << (PAGE_SHIFT + 3)) - 1);
+
+ set_bit(bit_index_residual, d->arch.dirty.bitmap[page_index]);
+}
+
+/* Routine for dirty-page tracing
+ *
+ * On first write, it page faults, its entry is changed to read-write,
+ * and on retry the write succeeds. For locating p2m of the faulting entry,
+ * we use virtual-linear page table.
+ *
+ * Returns zero if addr is not valid or dirty mode is not set
+ */
+int handle_page_fault(struct domain *d, paddr_t addr)
+{
+
+ lpae_t *vlp2m_pte = 0;
+ paddr_t gma_start = 0;
+ paddr_t gma_end = 0;
+
+ if ( !d->arch.dirty.mode )
+ return 0;
+
+ domain_get_gpfn_range(d, &gma_start, &gma_end);
+ /* Ensure that addr is inside guest's RAM */
+ if ( addr < gma_start || addr > gma_end )
+ return 0;
+
+ vlp2m_pte = get_vlpt_3lvl_pte(addr);
+ if ( vlp2m_pte->p2m.valid && vlp2m_pte->p2m.write == 0 &&
+ vlp2m_pte->p2m.type == p2m_ram_logdirty )
+ {
+ lpae_t pte = *vlp2m_pte;
+ pte.p2m.write = 1;
+ write_pte(vlp2m_pte, pte);
+ flush_tlb_local();
+
+ /* only necessary to lock between get-dirty bitmap and mark dirty
+ * bitmap. If get-dirty bitmap happens immediately before this
+ * lock, the corresponding dirty-page would be marked at the next
+ * round of get-dirty bitmap */
+ spin_lock(&d->arch.dirty.lock);
+ mark_dirty_bitmap(d, addr);
+ spin_unlock(&d->arch.dirty.lock);
+ }
+
+ return 1;
+}
+
+int prepare_bitmap(struct domain *d)
+{
+ paddr_t gma_start = 0;
+ paddr_t gma_end = 0;
+ int nr_bytes;
+ int nr_pages;
+ int i;
+
+ domain_get_gpfn_range(d, &gma_start, &gma_end);
+
+ nr_bytes = (PFN_DOWN(gma_end - gma_start) + 7) / 8;
+ nr_pages = (nr_bytes + PAGE_SIZE - 1) / PAGE_SIZE;
+
+ BUG_ON( nr_pages > MAX_DIRTY_BITMAP_PAGES );
+
+ for ( i = 0; i < nr_pages; ++i )
+ {
+ struct page_info *page;
+
+ page = alloc_domheap_page(NULL, 0);
+ if ( page == NULL )
+ goto cleanup_on_failure;
+
+ d->arch.dirty.bitmap[i] = map_domain_page_global(__page_to_mfn(page));
+ clear_page(d->arch.dirty.bitmap[i]);
+ }
+
+ d->arch.dirty.bitmap_pages = nr_pages;
+ return 0;
+
+cleanup_on_failure:
+ nr_pages = i;
+ for ( i = 0; i < nr_pages; ++i )
+ {
+ unmap_domain_page_global(d->arch.dirty.bitmap[i]);
+ }
+
+ return -ENOMEM;
+}
+
+void cleanup_bitmap(struct domain *d)
+{
+ int i;
+
+ for ( i = 0; i < d->arch.dirty.bitmap_pages; ++i )
+ {
+ unmap_domain_page_global(d->arch.dirty.bitmap[i]);
+ }
+}
+
/*
* Local variables:
* mode: C
diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
index 403fd89..d57a44a 100644
--- a/xen/arch/arm/p2m.c
+++ b/xen/arch/arm/p2m.c
@@ -6,6 +6,8 @@
#include <xen/bitops.h>
#include <asm/flushtlb.h>
#include <asm/gic.h>
+#include <xen/guest_access.h>
+#include <xen/pfn.h>
#include <asm/event.h>
#include <asm/hardirq.h>
#include <asm/page.h>
@@ -208,6 +210,7 @@ static lpae_t mfn_to_p2m_entry(unsigned long mfn, unsigned
int mattr,
break;
case p2m_ram_ro:
+ case p2m_ram_logdirty:
e.p2m.xn = 0;
e.p2m.write = 0;
break;
@@ -261,6 +264,10 @@ static int p2m_create_table(struct domain *d,
pte = mfn_to_p2m_entry(page_to_mfn(page), MATTR_MEM, p2m_invalid);
+ /* mark the write bit (page table's case, ro bit) as 0. So it is writable
+ * in case of vlpt access */
+ pte.pt.ro = 0;
+
write_pte(entry, pte);
return 0;
@@ -697,6 +704,210 @@ unsigned long gmfn_to_mfn(struct domain *d, unsigned long
gpfn)
return p >> PAGE_SHIFT;
}
+/* Change types across all p2m entries in a domain */
+void p2m_change_entry_type_global(struct domain *d, enum mg nt)
+{
+ struct p2m_domain *p2m = &d->arch.p2m;
+ paddr_t ram_base;
+ int i1, i2, i3;
+ int first_index, second_index, third_index;
+ lpae_t *first = __map_domain_page(p2m->first_level);
+ lpae_t pte, *second = NULL, *third = NULL;
+
+ domain_get_gpfn_range(d, &ram_base, NULL);
+
+ first_index = first_table_offset((uint64_t)ram_base);
+ second_index = second_table_offset((uint64_t)ram_base);
+ third_index = third_table_offset((uint64_t)ram_base);
+
+ BUG_ON( !first && "Can't map first level p2m." );
+
+ spin_lock(&p2m->lock);
+
+ for ( i1 = first_index; i1 < LPAE_ENTRIES*2; ++i1 )
+ {
+ lpae_walk_t first_pte = first[i1].walk;
+
+ if ( !first_pte.valid || !first_pte.table )
+ goto out;
+
+ second = map_domain_page(first_pte.base);
+ BUG_ON( !second && "Can't map second level p2m.");
+
+ for ( i2 = second_index; i2 < LPAE_ENTRIES; ++i2 )
+ {
+ lpae_walk_t second_pte = second[i2].walk;
+
+ if ( !second_pte.valid || !second_pte.table )
+ goto out;
+
+ third = map_domain_page(second_pte.base);
+ BUG_ON( !third && "Can't map third level p2m.");
+
+ for ( i3 = third_index; i3 < LPAE_ENTRIES; ++i3 )
+ {
+
+ lpae_walk_t third_pte = third[i3].walk;
+ if ( !third_pte.valid )
+ goto out;
+
+ pte = third[i3];
+ if ( nt == mg_ro )
+ {
+ if ( pte.p2m.write == 1 )
+ {
+ pte.p2m.write = 0;
+ pte.p2m.type = p2m_ram_logdirty;
+ }
+ else
+ {
+ /* reuse avail bit as an indicator of 'actual'
+ * read-only */
+ pte.p2m.type = p2m_ram_rw;
+ }
+ }
+ else if ( nt == mg_rw )
+ {
+ if ( pte.p2m.write == 0 &&
+ pte.p2m.type == p2m_ram_logdirty )
+ {
+ pte.p2m.write = p2m_ram_rw;
+ }
+ }
+ write_pte(&third[i3], pte);
+ }
+ unmap_domain_page(third);
+
+ third = NULL;
+ third_index = 0;
+ }
+ unmap_domain_page(second);
+
+ second = NULL;
+ second_index = 0;
+ third_index = 0;
+ }
+
+out:
+ flush_tlb_all_local();
+ if ( third ) unmap_domain_page(third);
+ if ( second ) unmap_domain_page(second);
+ if ( first ) unmap_domain_page(first);
+
+ spin_unlock(&p2m->lock);
+}
+
+/* Read a domain's log-dirty bitmap and stats.
+ * If the operation is a CLEAN, clear the bitmap and stats. */
+int log_dirty_op(struct domain *d, xen_domctl_shadow_op_t *sc)
+{
+ int peek = 1;
+ int i;
+ int bitmap_size;
+ paddr_t gma_start, gma_end;
+
+ /* this hypercall is called from domain 0, and we don't know which guest's
+ * vlpt is mapped in xen_second, so, to be sure, we restore vlpt here */
+ restore_vlpt(d);
+
+ domain_get_gpfn_range(d, &gma_start, &gma_end);
+ bitmap_size = (gma_end - gma_start) / 8;
+
+ if ( guest_handle_is_null(sc->dirty_bitmap) )
+ {
+ peek = 0;
+ }
+ else
+ {
+ spin_lock(&d->arch.dirty.lock);
+ for ( i = 0; i < d->arch.dirty.bitmap_pages; ++i )
+ {
+ int j = 0;
+ uint8_t *bitmap;
+ copy_to_guest_offset(sc->dirty_bitmap, i * PAGE_SIZE,
+ d->arch.dirty.bitmap[i],
+ bitmap_size < PAGE_SIZE ? bitmap_size :
+ PAGE_SIZE);
+ bitmap_size -= PAGE_SIZE;
+
+ /* set p2m page table read-only */
+ bitmap = d->arch.dirty.bitmap[i];
+ while ((j = find_next_bit((const long unsigned int *)bitmap,
+ PAGE_SIZE*8, j)) < PAGE_SIZE*8)
+ {
+ lpae_t *vlpt;
+ paddr_t addr = gma_start + (i << (2*PAGE_SHIFT+3)) +
+ (j << PAGE_SHIFT);
+ vlpt = get_vlpt_3lvl_pte(addr);
+ vlpt->p2m.write = 0;
+ j++;
+ }
+ }
+
+ if ( sc->op == XEN_DOMCTL_SHADOW_OP_CLEAN )
+ {
+ for ( i = 0; i < d->arch.dirty.bitmap_pages; ++i )
+ {
+ clear_page(d->arch.dirty.bitmap[i]);
+ }
+ }
+
+ spin_unlock(&d->arch.dirty.lock);
+ flush_tlb_local();
+ }
+
+ sc->stats.dirty_count = d->arch.dirty.count;
+
+ return 0;
+}
+
+long dirty_mode_op(struct domain *d, xen_domctl_shadow_op_t *sc)
+{
+ long ret = 0;
+ switch (sc->op)
+ {
+ case XEN_DOMCTL_SHADOW_OP_ENABLE_LOGDIRTY:
+ case XEN_DOMCTL_SHADOW_OP_OFF:
+ {
+ enum mg nt = sc->op == XEN_DOMCTL_SHADOW_OP_OFF ? mg_rw : mg_ro;
+
+ d->arch.dirty.mode = sc->op == XEN_DOMCTL_SHADOW_OP_OFF ? 0 : 1;
+ p2m_change_entry_type_global(d, nt);
+
+ if ( sc->op == XEN_DOMCTL_SHADOW_OP_OFF )
+ {
+ cleanup_vlpt(d);
+ cleanup_bitmap(d);
+ }
+ else
+ {
+ if ( (ret = prepare_vlpt(d)) )
+ return ret;
+
+ if ( (ret = prepare_bitmap(d)) )
+ {
+ /* in case of failure, we have to cleanup vlpt */
+ cleanup_vlpt(d);
+ return ret;
+ }
+ }
+ }
+ break;
+
+ case XEN_DOMCTL_SHADOW_OP_CLEAN:
+ case XEN_DOMCTL_SHADOW_OP_PEEK:
+ {
+ ret = log_dirty_op(d, sc);
+ }
+ break;
+
+ default:
+ return -ENOSYS;
+ }
+
+ return ret;
+}
+
/*
* Local variables:
* mode: C
diff --git a/xen/arch/arm/traps.c b/xen/arch/arm/traps.c
index a7edc4e..cca34e9 100644
--- a/xen/arch/arm/traps.c
+++ b/xen/arch/arm/traps.c
@@ -1491,6 +1491,8 @@ static void do_trap_data_abort_guest(struct cpu_user_regs
*regs,
struct hsr_dabt dabt = hsr.dabt;
int rc;
mmio_info_t info;
+ int page_fault = ( (dabt.dfsc & FSC_MASK) ==
+ (FSC_FLT_PERM | FSC_3D_LEVEL) && dabt.write );
if ( !check_conditional_instr(regs, hsr) )
{
@@ -1512,6 +1514,15 @@ static void do_trap_data_abort_guest(struct
cpu_user_regs *regs,
if ( rc == -EFAULT )
goto bad_data_abort;
+ /* domU page fault handling for guest live migration. dabt.valid can be
+ * 0 here.
+ */
+ if ( page_fault && handle_page_fault(current->domain, info.gpa) )
+ {
+ /* Do not modify pc after page fault to repeat memory operation */
+ return;
+ }
+
/* XXX: Decode the instruction if ISS is not valid */
if ( !dabt.valid )
goto bad_data_abort;
diff --git a/xen/include/asm-arm/domain.h b/xen/include/asm-arm/domain.h
index 5321bd6..99f9f51 100644
--- a/xen/include/asm-arm/domain.h
+++ b/xen/include/asm-arm/domain.h
@@ -163,9 +163,16 @@ struct arch_domain
/* dirty-page tracing */
struct {
+#define MAX_DIRTY_BITMAP_PAGES 64 /* support upto 8GB guest memory */
+ spinlock_t lock; /* protect list: head, mvn_head */
+ volatile int mode; /* 1 if dirty pages tracing enabled */
+ volatile unsigned int count; /* dirty pages counter */
volatile int second_lvl_start; /* for context switch */
volatile int second_lvl_end;
lpae_t *second_lvl[2]; /* copy of guest p2m's first */
+ /* dirty bitmap */
+ uint8_t *bitmap[MAX_DIRTY_BITMAP_PAGES];
+ int bitmap_pages; /* number of dirty bitmap pages */
} dirty;
unsigned int evtchn_irq;
diff --git a/xen/include/asm-arm/mm.h b/xen/include/asm-arm/mm.h
index 5fd684f..5f9478b 100644
--- a/xen/include/asm-arm/mm.h
+++ b/xen/include/asm-arm/mm.h
@@ -343,10 +343,18 @@ static inline void put_page_and_type(struct page_info
*page)
put_page(page);
}
+enum mg { mg_clear, mg_ro, mg_rw, mg_rx };
+
+/* routine for dirty-page tracing */
+int handle_page_fault(struct domain *d, paddr_t addr);
+
int prepare_vlpt(struct domain *d);
void cleanup_vlpt(struct domain *d);
void restore_vlpt(struct domain *d);
+int prepare_bitmap(struct domain *d);
+void cleanup_bitmap(struct domain *d);
+
/* calculate the xen's virtual address for accessing the leaf PTE of
* a given address (GPA) */
static inline lpae_t * get_vlpt_3lvl_pte(paddr_t addr)
@@ -359,6 +367,8 @@ static inline lpae_t * get_vlpt_3lvl_pte(paddr_t addr)
return &table[addr >> PAGE_SHIFT];
}
+void get_gma_start_end(struct domain *d, paddr_t *start, paddr_t *end);
+
#endif /* __ARCH_ARM_MM__ */
/*
* Local variables:
diff --git a/xen/include/asm-arm/p2m.h b/xen/include/asm-arm/p2m.h
index bd71abe..0cecbe7 100644
--- a/xen/include/asm-arm/p2m.h
+++ b/xen/include/asm-arm/p2m.h
@@ -2,6 +2,7 @@
#define _XEN_P2M_H
#include <xen/mm.h>
+#include <public/domctl.h>
struct domain;
@@ -41,6 +42,7 @@ typedef enum {
p2m_invalid = 0, /* Nothing mapped here */
p2m_ram_rw, /* Normal read/write guest RAM */
p2m_ram_ro, /* Read-only; writes are silently dropped */
+ p2m_ram_logdirty, /* Read-only: special mode for log dirty */
p2m_mmio_direct, /* Read/write mapping of genuine MMIO area */
p2m_map_foreign, /* Ram pages from foreign domain */
p2m_grant_map_rw, /* Read/write grant mapping */
@@ -49,7 +51,8 @@ typedef enum {
} p2m_type_t;
#define p2m_is_foreign(_t) ((_t) == p2m_map_foreign)
-#define p2m_is_ram(_t) ((_t) == p2m_ram_rw || (_t) == p2m_ram_ro)
+#define p2m_is_ram(_t) ((_t) == p2m_ram_rw || (_t) == p2m_ram_ro || \
+ (_t) == p2m_ram_logdirty)
/* Initialise vmid allocator */
void p2m_vmid_allocator_init(void);
@@ -178,6 +181,9 @@ static inline int get_page_and_type(struct page_info *page,
return rc;
}
+void p2m_change_entry_type_global(struct domain *d, enum mg nt);
+long dirty_mode_op(struct domain *d, xen_domctl_shadow_op_t *sc);
+
#endif /* _XEN_P2M_H */
/*
diff --git a/xen/include/asm-arm/processor.h b/xen/include/asm-arm/processor.h
index 06e638f..9dc49c3 100644
--- a/xen/include/asm-arm/processor.h
+++ b/xen/include/asm-arm/processor.h
@@ -399,6 +399,8 @@ union hsr {
#define FSC_CPR (0x3a) /* Coprocossor Abort */
#define FSC_LL_MASK (_AC(0x03,U)<<0)
+#define FSC_MASK (0x3f) /* Fault status mask */
+#define FSC_3D_LEVEL (0x03) /* Third level fault*/
/* Time counter hypervisor control register */
#define CNTHCTL_PA (1u<<0) /* Kernel/user access to physical counter */
--
1.7.9.5
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