diff mbox series

[v2,03/18] x86/mm: introduce helper to detect per-domain L1 entries that need freeing

Message ID 20250108142659.99490-4-roger.pau@citrix.com (mailing list archive)
State New
Headers show
Series x86: adventures in Address Space Isolation | expand

Commit Message

Roger Pau Monné Jan. 8, 2025, 2:26 p.m. UTC 
L1 present entries that require the underlying page to be freed have the
_PAGE_AVAIL0 bit set, introduce a helper to unify the checking logic into a
single place.

No functional change intended.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
---
 xen/arch/x86/mm.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

Comments

Jan Beulich Jan. 9, 2025, 9:03 a.m. UTC | #1 
On 08.01.2025 15:26, Roger Pau Monne wrote:
> L1 present entries that require the underlying page to be freed have the
> _PAGE_AVAIL0 bit set, introduce a helper to unify the checking logic into a
> single place.
> 
> No functional change intended.
> 
> Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>

Reviewed-by: Jan Beulich <jbeulich@suse.com>

The name feels longish, yet perhaps that's acceptable here.

Jan
diff mbox series

Patch

diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c
index fa21903eb25a..3d5dd22b6c36 100644
--- a/xen/arch/x86/mm.c
+++ b/xen/arch/x86/mm.c
@@ -6294,6 +6294,12 @@  void __iomem *__init ioremap_wc(paddr_t pa, size_t len)
     return (void __force __iomem *)(va + offs);
 }
 
+static bool perdomain_l1e_needs_freeing(l1_pgentry_t l1e)
+{
+    return (l1e_get_flags(l1e) & (_PAGE_PRESENT | _PAGE_AVAIL0)) ==
+           (_PAGE_PRESENT | _PAGE_AVAIL0);
+}
+
 int create_perdomain_mapping(struct domain *d, unsigned long va,
                              unsigned int nr, l1_pgentry_t **pl1tab,
                              struct page_info **ppg)
@@ -6446,9 +6452,7 @@  void destroy_perdomain_mapping(struct domain *d, unsigned long va,
 
                 for ( ; nr && i < L1_PAGETABLE_ENTRIES; --nr, ++i )
                 {
-                    if ( (l1e_get_flags(l1tab[i]) &
-                          (_PAGE_PRESENT | _PAGE_AVAIL0)) ==
-                         (_PAGE_PRESENT | _PAGE_AVAIL0) )
+                    if ( perdomain_l1e_needs_freeing(l1tab[i]) )
                         free_domheap_page(l1e_get_page(l1tab[i]));
                     l1tab[i] = l1e_empty();
                 }
@@ -6498,9 +6502,7 @@  void free_perdomain_mappings(struct domain *d)
                         unsigned int k;
 
                         for ( k = 0; k < L1_PAGETABLE_ENTRIES; ++k )
-                            if ( (l1e_get_flags(l1tab[k]) &
-                                  (_PAGE_PRESENT | _PAGE_AVAIL0)) ==
-                                 (_PAGE_PRESENT | _PAGE_AVAIL0) )
+                            if ( perdomain_l1e_needs_freeing(l1tab[k]) )
                                 free_domheap_page(l1e_get_page(l1tab[k]));
 
                         unmap_domain_page(l1tab);