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x86/p2m: {get,set}_entry hooks and p2m-pt.c are HVM-only
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With the hooks no longer needing setting, p2m_pt_init() degenerates to
(about) nothing when !HVM. As a result, p2m-pt.c doesn't need building
anymore in this case, as long as p2m_pt_init() has proper surrogates put
in place.

Unfortunately this means some new #ifdef-ary in p2m.c, but the mid-term
plan there is to get rid of (almost) all of it by splitting out the then
hopefully very few remaining non-HVM pieces.

While the movement of the paging_mode_translate() check from
p2m_remove_page() to guest_physmap_remove_page() may not be strictly
necessary anymore (it was in an early version of this change), it looks
more logical to live in the latter function, allowing to avoid acquiring
the lock in the PV case. All other callers of p2m_remove_page() already
have such a check anyway (in the altp2m case up the call stack).

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Roger Pau Monné <roger.pau@citrix.com>
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jbeulich committed May 3, 2021
1 parent 936830c commit 8d012d3
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Showing 5 changed files with 41 additions and 16 deletions.
4 changes: 2 additions & 2 deletions xen/arch/x86/mm/Makefile
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Original file line number Diff line number Diff line change
Expand Up @@ -7,8 +7,8 @@ obj-$(CONFIG_SHADOW_PAGING) += guest_walk_4.o
obj-$(CONFIG_MEM_ACCESS) += mem_access.o
obj-$(CONFIG_MEM_PAGING) += mem_paging.o
obj-$(CONFIG_MEM_SHARING) += mem_sharing.o
obj-y += p2m.o p2m-pt.o
obj-$(CONFIG_HVM) += p2m-ept.o p2m-pod.o
obj-y += p2m.o
obj-$(CONFIG_HVM) += p2m-ept.o p2m-pod.o p2m-pt.o
obj-y += paging.o

guest_walk_%.o: guest_walk.c Makefile
Expand Down
8 changes: 0 additions & 8 deletions xen/arch/x86/mm/p2m-pt.c
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Original file line number Diff line number Diff line change
Expand Up @@ -324,7 +324,6 @@ p2m_next_level(struct p2m_domain *p2m, void **table,
return rc;
}

#ifdef CONFIG_HVM
/*
* Mark (via clearing the U flag) as needing P2M type re-calculation all valid
* present entries at the targeted level for the passed in GFN range, which is
Expand Down Expand Up @@ -393,7 +392,6 @@ static int p2m_pt_set_recalc_range(struct p2m_domain *p2m,

return err;
}
#endif /* CONFIG_HVM */

/*
* Handle possibly necessary P2M type re-calculation (U flag clear for a
Expand Down Expand Up @@ -932,8 +930,6 @@ p2m_pt_get_entry(struct p2m_domain *p2m, gfn_t gfn_,
return (p2m_is_valid(*t) || p2m_is_any_ram(*t)) ? mfn : INVALID_MFN;
}

#ifdef CONFIG_HVM

static void p2m_pt_change_entry_type_global(struct p2m_domain *p2m,
p2m_type_t ot, p2m_type_t nt)
{
Expand Down Expand Up @@ -1015,8 +1011,6 @@ static int p2m_pt_change_entry_type_range(struct p2m_domain *p2m,
return err;
}

#endif /* CONFIG_HVM */

#if P2M_AUDIT
static long p2m_pt_audit_p2m(struct p2m_domain *p2m)
{
Expand Down Expand Up @@ -1173,11 +1167,9 @@ void p2m_pt_init(struct p2m_domain *p2m)
{
p2m->set_entry = p2m_pt_set_entry;
p2m->get_entry = p2m_pt_get_entry;
#ifdef CONFIG_HVM
p2m->recalc = do_recalc;
p2m->change_entry_type_global = p2m_pt_change_entry_type_global;
p2m->change_entry_type_range = p2m_pt_change_entry_type_range;
#endif

/* Still too early to use paging_mode_hap(). */
if ( hap_enabled(p2m->domain) )
Expand Down
28 changes: 23 additions & 5 deletions xen/arch/x86/mm/p2m.c
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Original file line number Diff line number Diff line change
Expand Up @@ -494,8 +494,10 @@ mfn_t __get_gfn_type_access(struct p2m_domain *p2m, unsigned long gfn_l,
p2m_type_t *t, p2m_access_t *a, p2m_query_t q,
unsigned int *page_order, bool_t locked)
{
#ifdef CONFIG_HVM
mfn_t mfn;
gfn_t gfn = _gfn(gfn_l);
#endif

/* Unshare makes no sense withuot populate. */
if ( q & P2M_UNSHARE )
Expand All @@ -509,6 +511,7 @@ mfn_t __get_gfn_type_access(struct p2m_domain *p2m, unsigned long gfn_l,
return _mfn(gfn_l);
}

#ifdef CONFIG_HVM
if ( locked )
/* Grab the lock here, don't release until put_gfn */
gfn_lock(p2m, gfn, 0);
Expand Down Expand Up @@ -542,6 +545,7 @@ mfn_t __get_gfn_type_access(struct p2m_domain *p2m, unsigned long gfn_l,
}

return mfn;
#endif
}

void __put_gfn(struct p2m_domain *p2m, unsigned long gfn)
Expand Down Expand Up @@ -620,6 +624,7 @@ struct page_info *p2m_get_page_from_gfn(
return page;
}

#ifdef CONFIG_HVM
/* Returns: 0 for success, -errno for failure */
int p2m_set_entry(struct p2m_domain *p2m, gfn_t gfn, mfn_t mfn,
unsigned int page_order, p2m_type_t p2mt, p2m_access_t p2ma)
Expand Down Expand Up @@ -659,6 +664,7 @@ int p2m_set_entry(struct p2m_domain *p2m, gfn_t gfn, mfn_t mfn,

return rc;
}
#endif

mfn_t p2m_alloc_ptp(struct p2m_domain *p2m, unsigned int level)
{
Expand Down Expand Up @@ -777,6 +783,8 @@ void p2m_final_teardown(struct domain *d)
p2m_teardown_hostp2m(d);
}

#ifdef CONFIG_HVM

static int __must_check
p2m_remove_page(struct p2m_domain *p2m, gfn_t gfn, mfn_t mfn,
unsigned int page_order)
Expand All @@ -785,10 +793,6 @@ p2m_remove_page(struct p2m_domain *p2m, gfn_t gfn, mfn_t mfn,
p2m_type_t t;
p2m_access_t a;

/* IOMMU for PV guests is handled in get_page_type() and put_page(). */
if ( !paging_mode_translate(p2m->domain) )
return 0;

ASSERT(gfn_locked_by_me(p2m, gfn));
P2M_DEBUG("removing gfn=%#lx mfn=%#lx\n", gfn_x(gfn), mfn_x(mfn));

Expand Down Expand Up @@ -829,13 +833,19 @@ guest_physmap_remove_page(struct domain *d, gfn_t gfn,
struct p2m_domain *p2m = p2m_get_hostp2m(d);
int rc;

/* IOMMU for PV guests is handled in get_page_type() and put_page(). */
if ( !paging_mode_translate(d) )
return 0;

gfn_lock(p2m, gfn, page_order);
rc = p2m_remove_page(p2m, gfn, mfn, page_order);
gfn_unlock(p2m, gfn, page_order);

return rc;
}

#endif /* CONFIG_HVM */

int
guest_physmap_add_page(struct domain *d, gfn_t gfn, mfn_t mfn,
unsigned int page_order)
Expand Down Expand Up @@ -1400,14 +1410,16 @@ int clear_mmio_p2m_entry(struct domain *d, unsigned long gfn_l, mfn_t mfn,
int set_identity_p2m_entry(struct domain *d, unsigned long gfn_l,
p2m_access_t p2ma, unsigned int flag)
{
#ifdef CONFIG_HVM
p2m_type_t p2mt;
p2m_access_t a;
gfn_t gfn = _gfn(gfn_l);
mfn_t mfn;
struct p2m_domain *p2m = p2m_get_hostp2m(d);
int ret;
#endif

if ( !paging_mode_translate(p2m->domain) )
if ( !paging_mode_translate(d) )
{
if ( !is_iommu_enabled(d) )
return 0;
Expand All @@ -1416,6 +1428,7 @@ int set_identity_p2m_entry(struct domain *d, unsigned long gfn_l,
IOMMUF_readable | IOMMUF_writable);
}

#ifdef CONFIG_HVM
gfn_lock(p2m, gfn, 0);

mfn = p2m->get_entry(p2m, gfn, &p2mt, &a, 0, NULL, NULL);
Expand All @@ -1439,16 +1452,19 @@ int set_identity_p2m_entry(struct domain *d, unsigned long gfn_l,

gfn_unlock(p2m, gfn, 0);
return ret;
#endif
}

int clear_identity_p2m_entry(struct domain *d, unsigned long gfn_l)
{
#ifdef CONFIG_HVM
p2m_type_t p2mt;
p2m_access_t a;
gfn_t gfn = _gfn(gfn_l);
mfn_t mfn;
struct p2m_domain *p2m = p2m_get_hostp2m(d);
int ret;
#endif

if ( !paging_mode_translate(d) )
{
Expand All @@ -1457,6 +1473,7 @@ int clear_identity_p2m_entry(struct domain *d, unsigned long gfn_l)
return iommu_legacy_unmap(d, _dfn(gfn_l), 1ul << PAGE_ORDER_4K);
}

#ifdef CONFIG_HVM
gfn_lock(p2m, gfn, 0);

mfn = p2m->get_entry(p2m, gfn, &p2mt, &a, 0, NULL, NULL);
Expand All @@ -1476,6 +1493,7 @@ int clear_identity_p2m_entry(struct domain *d, unsigned long gfn_l)
}

return ret;
#endif
}

#ifdef CONFIG_MEM_SHARING
Expand Down
8 changes: 7 additions & 1 deletion xen/include/asm-x86/p2m.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -251,6 +251,7 @@ struct p2m_domain {
/* Pages used to construct the p2m */
struct page_list_head pages;

#ifdef CONFIG_HVM
int (*set_entry)(struct p2m_domain *p2m,
gfn_t gfn,
mfn_t mfn, unsigned int page_order,
Expand All @@ -264,7 +265,6 @@ struct p2m_domain {
p2m_query_t q,
unsigned int *page_order,
bool_t *sve);
#ifdef CONFIG_HVM
int (*recalc)(struct p2m_domain *p2m,
unsigned long gfn);
void (*enable_hardware_log_dirty)(struct p2m_domain *p2m);
Expand Down Expand Up @@ -793,8 +793,14 @@ int __must_check p2m_set_entry(struct p2m_domain *p2m, gfn_t gfn, mfn_t mfn,
unsigned int page_order, p2m_type_t p2mt,
p2m_access_t p2ma);

#if defined(CONFIG_HVM)
/* Set up function pointers for PT implementation: only for use by p2m code */
extern void p2m_pt_init(struct p2m_domain *p2m);
#elif defined(CONFIG_SHADOW_PAGING)
# define p2m_pt_init shadow_p2m_init
#else
static inline void p2m_pt_init(struct p2m_domain *p2m) {}
#endif

void *map_domain_gfn(struct p2m_domain *p2m, gfn_t gfn, mfn_t *mfn,
p2m_query_t q, uint32_t *pfec);
Expand Down
9 changes: 9 additions & 0 deletions xen/include/xen/p2m-common.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -8,9 +8,18 @@ int set_foreign_p2m_entry(struct domain *d, const struct domain *fd,
unsigned long gfn, mfn_t mfn);

/* Remove a page from a domain's p2m table */
#ifdef CONFIG_HVM
int __must_check
guest_physmap_remove_page(struct domain *d, gfn_t gfn, mfn_t mfn,
unsigned int page_order);
#else
static inline int
guest_physmap_remove_page(struct domain *d, gfn_t gfn, mfn_t mfn,
unsigned int page_order)
{
return 0;
}
#endif

/* Map MMIO regions in the p2m: start_gfn and nr describe the range in
* * the guest physical address space to map, starting from the machine
Expand Down

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