[PATCH v3 03/18] x86/mm: prepare destroy_perdomain_mapping() for per-vCPU perdomain areas

[George Dunlap <gwd@xxxxxxxxxxxxxx>]

From: Roger Pau Monné <roger.pau@xxxxxxxxxx>

We want to change per-domain mappings to be per-vCPU mappings.  In
preparation for that, we want to arrange that
destroy_perdomain_mapping() work either with a single perdomain area,
or with a per-vCPU perdomain area.

The one remaining caller, free_compat_arg_xlat(), is already in a vCPU
context, so we just need to change the parameter from a domain pointer
to a vCPU pointer.

Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
Assisted-by: Claude Code:claude-fable-5, Claude Code:claude-opus-4-8, Claude 
Code:claude-opus-5-5
Signed-off-by: George Dunlap <gwd@xxxxxxxxxxxxxx>
---
Changes in v3:
- Rebased onto staging without the GDT/LDT conversions (for the
  HVM-only series): free_compat_arg_xlat() is the only caller left.
- Drop the linear-page-table fast path altogether (Jan): its only user
  would have been guest-driven LDT teardown, and without it the
  function does not depend on the linear mapping being available.

Changes in v2:
- Added to the series

Changes since the previously posted version:
- The fast path is gone (v3), and with it the previously posted
  version's sync_local_execstate() call.
- Reword and retitle for clarity (was: "x86/mm: switch
  destroy_perdomain_mapping() parameter from domain to vCPU").
---
 xen/arch/x86/include/asm/mm.h | 2 +-
 xen/arch/x86/mm.c             | 3 ++-
 xen/arch/x86/x86_64/mm.c      | 2 +-
 3 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/xen/arch/x86/include/asm/mm.h b/xen/arch/x86/include/asm/mm.h
index 2254a7e3fe..b19b1ae53f 100644
--- a/xen/arch/x86/include/asm/mm.h
+++ b/xen/arch/x86/include/asm/mm.h
@@ -606,7 +606,7 @@ int compat_arch_memory_op(unsigned long cmd, 
XEN_GUEST_HANDLE_PARAM(void) arg);
 int create_perdomain_mapping(struct domain *d, unsigned long va,
                              unsigned int nr, l1_pgentry_t **pl1tab,
                              struct page_info **ppg);
-void destroy_perdomain_mapping(struct domain *d, unsigned long va,
+void destroy_perdomain_mapping(const struct vcpu *v, unsigned long va,
                                unsigned int nr);
 void free_perdomain_mappings(struct domain *d);
 
diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c
index b158742408..769b9b3016 100644
--- a/xen/arch/x86/mm.c
+++ b/xen/arch/x86/mm.c
@@ -6334,10 +6334,11 @@ int create_perdomain_mapping(struct domain *d, unsigned 
long va,
     return rc;
 }
 
-void destroy_perdomain_mapping(struct domain *d, unsigned long va,
+void destroy_perdomain_mapping(const struct vcpu *v, unsigned long va,
                                unsigned int nr)
 {
     const l3_pgentry_t *l3tab, *pl3e;
+    const struct domain *d = v->domain;
 
     ASSERT(va >= PERDOMAIN_VIRT_START &&
            va < PERDOMAIN_VIRT_SLOT(PERDOMAIN_SLOTS));
diff --git a/xen/arch/x86/x86_64/mm.c b/xen/arch/x86/x86_64/mm.c
index 2a1805964d..8c576acdc7 100644
--- a/xen/arch/x86/x86_64/mm.c
+++ b/xen/arch/x86/x86_64/mm.c
@@ -744,7 +744,7 @@ int setup_compat_arg_xlat(struct vcpu *v)
  */
 void free_compat_arg_xlat(struct vcpu *v)
 {
-    destroy_perdomain_mapping(v->domain, ARG_XLAT_START(v),
+    destroy_perdomain_mapping(v, ARG_XLAT_START(v),
                               PFN_UP(COMPAT_ARG_XLAT_SIZE));
 }
 
-- 
2.55.0