[xen staging] x86/P2M: don't include MMIO_DM in p2m_is_valid()

[patchbot@xxxxxxx]

commit be59cceb2dbbea3815f35f6982aac6d2ab1b10b7
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Tue Mar 11 09:55:47 2025 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Tue Mar 11 09:55:47 2025 +0100

    x86/P2M: don't include MMIO_DM in p2m_is_valid()
    
    MMIO_DM specifically marks pages which aren't valid, much like INVALID
    does. Dropping the type from the predicate
    - (conceptually) corrects _sh_propagate(), where the comment says that
      "something valid" is needed (the only call path not passing in RAM_RW
      would pass in INVALID_GFN along with MMIO_DM),
    - is benign to the use in sh_page_fault(), where the subsequent
      mfn_valid() check would otherwise cause the same bail-out code path to
      be taken,
    - is benign to all three uses in p2m_pt_get_entry(), as MMIO_DM entries
      will only ever yield non-present entries, which are being checked for
      earlier,
    - is benign to sh_unshadow_for_p2m_change(), for the same reason,
    - is benign to gnttab_transfer() with EPT not in use, again because
      MMIO_DM entries will only ever yield non-present entries, and
      INVALID_MFN is returned for those anyway by p2m_pt_get_entry().
    - for gnttab_transfer() with EPT in use (conceptually) corrects the
      corner case of a page first being subject to XEN_DMOP_set_mem_type
      converting a RAM type to MMIO_DM (which retains the MFN in the entry),
      and then being subject to GNTTABOP_transfer, except that steal_page()
      would later make the operation fail unconditionally anyway.
    
    While there also drop the unused (and otherwise now redundant)
    p2m_has_emt().
    
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Acked-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
---
 xen/arch/x86/include/asm/p2m.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/xen/arch/x86/include/asm/p2m.h b/xen/arch/x86/include/asm/p2m.h
index aa1bf7c9d0..6816a1be91 100644
--- a/xen/arch/x86/include/asm/p2m.h
+++ b/xen/arch/x86/include/asm/p2m.h
@@ -168,8 +168,8 @@ typedef unsigned int p2m_query_t;
 /* Grant types are *not* considered valid, because they can be
    unmapped at any time and, unless you happen to be the shadow or p2m
    implementations, there's no way of synchronising against that. */
-#define p2m_is_valid(_t) (p2m_to_mask(_t) & (P2M_RAM_TYPES | P2M_MMIO_TYPES))
-#define p2m_has_emt(_t)  (p2m_to_mask(_t) & (P2M_RAM_TYPES | 
p2m_to_mask(p2m_mmio_direct)))
+#define p2m_is_valid(_t)    (p2m_to_mask(_t) & \
+                             (P2M_RAM_TYPES | p2m_to_mask(p2m_mmio_direct)))
 #define p2m_is_pageable(_t) (p2m_to_mask(_t) & P2M_PAGEABLE_TYPES)
 #define p2m_is_paging(_t)   (p2m_to_mask(_t) & P2M_PAGING_TYPES)
 #define p2m_is_paged(_t)    (p2m_to_mask(_t) & P2M_PAGED_TYPES)
--
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