diff options
Diffstat (limited to '0077-x86-shadow-fix-and-improve-sh_page_has_multiple_shad.patch')
| -rw-r--r-- | 0077-x86-shadow-fix-and-improve-sh_page_has_multiple_shad.patch | 47 |
1 files changed, 0 insertions, 47 deletions
diff --git a/0077-x86-shadow-fix-and-improve-sh_page_has_multiple_shad.patch b/0077-x86-shadow-fix-and-improve-sh_page_has_multiple_shad.patch deleted file mode 100644 index 3486ccd..0000000 --- a/0077-x86-shadow-fix-and-improve-sh_page_has_multiple_shad.patch +++ /dev/null @@ -1,47 +0,0 @@ -From 6f2d89d68175e74aca9c67761aa87ffc8f5ffed1 Mon Sep 17 00:00:00 2001 -From: Jan Beulich <jbeulich@suse.com> -Date: Fri, 31 Mar 2023 08:30:41 +0200 -Subject: [PATCH 77/89] x86/shadow: fix and improve - sh_page_has_multiple_shadows() - -While no caller currently invokes the function without first making sure -there is at least one shadow [1], we'd better eliminate UB here: -find_first_set_bit() requires input to be non-zero to return a well- -defined result. - -Further, using find_first_set_bit() isn't very efficient in the first -place for the intended purpose. - -Signed-off-by: Jan Beulich <jbeulich@suse.com> -Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com> - -[1] The function has exactly two uses, and both are from OOS code, which - is HVM-only. For HVM (but not for PV) sh_mfn_is_a_page_table(), - guarding the call to sh_unsync(), guarantees at least one shadow. - Hence even if sh_page_has_multiple_shadows() returned a bogus value - when invoked for a PV domain, the subsequent is_hvm_vcpu() and - oos_active checks (the former being redundant with the latter) will - compensate. (Arguably that oos_active check should come first, for - both clarity and efficiency reasons.) -master commit: 2896224a4e294652c33f487b603d20bd30955f21 -master date: 2023-03-24 11:07:08 +0100 ---- - xen/arch/x86/mm/shadow/private.h | 2 +- - 1 file changed, 1 insertion(+), 1 deletion(-) - -diff --git a/xen/arch/x86/mm/shadow/private.h b/xen/arch/x86/mm/shadow/private.h -index 85bb26c7ea..c2bb1ed3c3 100644 ---- a/xen/arch/x86/mm/shadow/private.h -+++ b/xen/arch/x86/mm/shadow/private.h -@@ -324,7 +324,7 @@ static inline int sh_page_has_multiple_shadows(struct page_info *pg) - return 0; - shadows = pg->shadow_flags & SHF_page_type_mask; - /* More than one type bit set in shadow-flags? */ -- return ( (shadows & ~(1UL << find_first_set_bit(shadows))) != 0 ); -+ return shadows && (shadows & (shadows - 1)); - } - - #if (SHADOW_OPTIMIZATIONS & SHOPT_OUT_OF_SYNC) --- -2.40.0 - |