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x86/mm: switch to new APIs in modify_xen_mappings
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Page tables allocated in that function should be mapped and unmapped
now.

Note that pl2e now maybe mapped and unmapped in different iterations, so
we need to add clean-ups for that.

Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: Hongyan Xia <hongyxia@amazon.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
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@jbeulich
Wei Liu authored and jbeulich committed Apr 22, 2021
1 parent 4b5b083 commit dd68f2e
Showing 1 changed file with 36 additions and 21 deletions.
57 changes: 36 additions & 21 deletions xen/arch/x86/mm.c
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Original file line number Diff line number Diff line change
Expand Up @@ -5546,6 +5546,7 @@ int map_pages_to_xen(

out:
L3T_UNLOCK(current_l3page);
unmap_domain_page(pl2e);
unmap_domain_page(pl3e);
unmap_domain_page(pl2e);
return rc;
Expand All @@ -5572,7 +5573,7 @@ int modify_xen_mappings(unsigned long s, unsigned long e, unsigned int nf)
{
bool locking = system_state > SYS_STATE_boot;
l3_pgentry_t *pl3e = NULL;
l2_pgentry_t *pl2e;
l2_pgentry_t *pl2e = NULL;
l1_pgentry_t *pl1e;
unsigned int i;
unsigned long v = s;
Expand All @@ -5592,6 +5593,7 @@ int modify_xen_mappings(unsigned long s, unsigned long e, unsigned int nf)
{
/* Clean up the previous iteration. */
L3T_UNLOCK(current_l3page);
UNMAP_DOMAIN_PAGE(pl2e);
UNMAP_DOMAIN_PAGE(pl3e);

pl3e = virt_to_xen_l3e(v);
Expand All @@ -5614,6 +5616,7 @@ int modify_xen_mappings(unsigned long s, unsigned long e, unsigned int nf)
if ( l3e_get_flags(*pl3e) & _PAGE_PSE )
{
l2_pgentry_t *l2t;
mfn_t l2mfn;

if ( l2_table_offset(v) == 0 &&
l1_table_offset(v) == 0 &&
Expand All @@ -5630,35 +5633,38 @@ int modify_xen_mappings(unsigned long s, unsigned long e, unsigned int nf)
}

/* PAGE1GB: shatter the superpage and fall through. */
l2t = alloc_xen_pagetable();
if ( !l2t )
l2mfn = alloc_xen_pagetable_new();
if ( mfn_eq(l2mfn, INVALID_MFN) )
goto out;

l2t = map_domain_page(l2mfn);
for ( i = 0; i < L2_PAGETABLE_ENTRIES; i++ )
l2e_write(l2t + i,
l2e_from_pfn(l3e_get_pfn(*pl3e) +
(i << PAGETABLE_ORDER),
l3e_get_flags(*pl3e)));
UNMAP_DOMAIN_PAGE(l2t);

if ( locking )
spin_lock(&map_pgdir_lock);
if ( (l3e_get_flags(*pl3e) & _PAGE_PRESENT) &&
(l3e_get_flags(*pl3e) & _PAGE_PSE) )
{
l3e_write_atomic(pl3e, l3e_from_mfn(virt_to_mfn(l2t),
__PAGE_HYPERVISOR));
l2t = NULL;
l3e_write_atomic(pl3e,
l3e_from_mfn(l2mfn, __PAGE_HYPERVISOR));
l2mfn = INVALID_MFN;
}
if ( locking )
spin_unlock(&map_pgdir_lock);
if ( l2t )
free_xen_pagetable(l2t);

free_xen_pagetable_new(l2mfn);
}

/*
* The L3 entry has been verified to be present, and we've dealt with
* 1G pages as well, so the L2 table cannot require allocation.
*/
pl2e = l3e_to_l2e(*pl3e) + l2_table_offset(v);
pl2e = map_l2t_from_l3e(*pl3e) + l2_table_offset(v);

if ( !(l2e_get_flags(*pl2e) & _PAGE_PRESENT) )
{
Expand Down Expand Up @@ -5686,41 +5692,45 @@ int modify_xen_mappings(unsigned long s, unsigned long e, unsigned int nf)
else
{
l1_pgentry_t *l1t;

/* PSE: shatter the superpage and try again. */
l1t = alloc_xen_pagetable();
if ( !l1t )
mfn_t l1mfn = alloc_xen_pagetable_new();

if ( mfn_eq(l1mfn, INVALID_MFN) )
goto out;

l1t = map_domain_page(l1mfn);
for ( i = 0; i < L1_PAGETABLE_ENTRIES; i++ )
l1e_write(&l1t[i],
l1e_from_pfn(l2e_get_pfn(*pl2e) + i,
l2e_get_flags(*pl2e) & ~_PAGE_PSE));
UNMAP_DOMAIN_PAGE(l1t);

if ( locking )
spin_lock(&map_pgdir_lock);
if ( (l2e_get_flags(*pl2e) & _PAGE_PRESENT) &&
(l2e_get_flags(*pl2e) & _PAGE_PSE) )
{
l2e_write_atomic(pl2e, l2e_from_mfn(virt_to_mfn(l1t),
l2e_write_atomic(pl2e, l2e_from_mfn(l1mfn,
__PAGE_HYPERVISOR));
l1t = NULL;
l1mfn = INVALID_MFN;
}
if ( locking )
spin_unlock(&map_pgdir_lock);
if ( l1t )
free_xen_pagetable(l1t);

free_xen_pagetable_new(l1mfn);
}
}
else
{
l1_pgentry_t nl1e, *l1t;
mfn_t l1mfn;

/*
* Ordinary 4kB mapping: The L2 entry has been verified to be
* present, and we've dealt with 2M pages as well, so the L1 table
* cannot require allocation.
*/
pl1e = l2e_to_l1e(*pl2e) + l1_table_offset(v);
pl1e = map_l1t_from_l2e(*pl2e) + l1_table_offset(v);

/* Confirm the caller isn't trying to create new mappings. */
if ( !(l1e_get_flags(*pl1e) & _PAGE_PRESENT) )
Expand All @@ -5731,6 +5741,7 @@ int modify_xen_mappings(unsigned long s, unsigned long e, unsigned int nf)
(l1e_get_flags(*pl1e) & ~FLAGS_MASK) | nf);

l1e_write_atomic(pl1e, nl1e);
UNMAP_DOMAIN_PAGE(pl1e);
v += PAGE_SIZE;

/*
Expand Down Expand Up @@ -5760,18 +5771,20 @@ int modify_xen_mappings(unsigned long s, unsigned long e, unsigned int nf)
continue;
}

l1t = l2e_to_l1e(*pl2e);
l1mfn = l2e_get_mfn(*pl2e);
l1t = map_domain_page(l1mfn);
for ( i = 0; i < L1_PAGETABLE_ENTRIES; i++ )
if ( l1e_get_intpte(l1t[i]) != 0 )
break;
UNMAP_DOMAIN_PAGE(l1t);
if ( i == L1_PAGETABLE_ENTRIES )
{
/* Empty: zap the L2E and free the L1 page. */
l2e_write_atomic(pl2e, l2e_empty());
if ( locking )
spin_unlock(&map_pgdir_lock);
flush_area(NULL, FLUSH_TLB_GLOBAL); /* flush before free */
free_xen_pagetable(l1t);
free_xen_pagetable_new(l1mfn);
}
else if ( locking )
spin_unlock(&map_pgdir_lock);
Expand Down Expand Up @@ -5802,19 +5815,21 @@ int modify_xen_mappings(unsigned long s, unsigned long e, unsigned int nf)

{
l2_pgentry_t *l2t;
mfn_t l2mfn = l3e_get_mfn(*pl3e);

l2t = l3e_to_l2e(*pl3e);
l2t = map_domain_page(l2mfn);
for ( i = 0; i < L2_PAGETABLE_ENTRIES; i++ )
if ( l2e_get_intpte(l2t[i]) != 0 )
break;
UNMAP_DOMAIN_PAGE(l2t);
if ( i == L2_PAGETABLE_ENTRIES )
{
/* Empty: zap the L3E and free the L2 page. */
l3e_write_atomic(pl3e, l3e_empty());
if ( locking )
spin_unlock(&map_pgdir_lock);
flush_area(NULL, FLUSH_TLB_GLOBAL); /* flush before free */
free_xen_pagetable(l2t);
free_xen_pagetable_new(l2mfn);
}
else if ( locking )
spin_unlock(&map_pgdir_lock);
Expand Down

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