[xen master] xen/riscv: introduce things necessary for p2m initialization

[patchbot@xxxxxxx]

commit 45434df6082e8323ca666ee4d53326b1a4eeeb09
Author:     Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>
AuthorDate: Tue Dec 16 17:55:13 2025 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Thu Dec 18 09:59:16 2025 +0100

    xen/riscv: introduce things necessary for p2m initialization
    
    Introduce the following things:
    - Update p2m_domain structure, which describe per p2m-table state, with:
      - lock to protect updates to p2m.
      - pool with pages used to construct p2m.
      - back pointer to domain structure.
    - p2m_init() to initalize members introduced in p2m_domain structure.
    
    Signed-off-by: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>
    Acked-by: Jan Beulich <jbeulich@xxxxxxxx>
---
 xen/arch/riscv/include/asm/domain.h |  5 +++++
 xen/arch/riscv/include/asm/p2m.h    | 33 +++++++++++++++++++++++++++++++++
 xen/arch/riscv/p2m.c                | 20 ++++++++++++++++++++
 3 files changed, 58 insertions(+)

diff --git a/xen/arch/riscv/include/asm/domain.h 
b/xen/arch/riscv/include/asm/domain.h
index aac1040658..e688980efa 100644
--- a/xen/arch/riscv/include/asm/domain.h
+++ b/xen/arch/riscv/include/asm/domain.h
@@ -5,6 +5,8 @@
 #include <xen/xmalloc.h>
 #include <public/hvm/params.h>
 
+#include <asm/p2m.h>
+
 struct vcpu_vmid {
     uint64_t generation;
     uint16_t vmid;
@@ -24,6 +26,9 @@ struct arch_vcpu {
 
 struct arch_domain {
     struct hvm_domain hvm;
+
+    /* Virtual MMU */
+    struct p2m_domain p2m;
 };
 
 #include <xen/sched.h>
diff --git a/xen/arch/riscv/include/asm/p2m.h b/xen/arch/riscv/include/asm/p2m.h
index 3776b98303..239f90622e 100644
--- a/xen/arch/riscv/include/asm/p2m.h
+++ b/xen/arch/riscv/include/asm/p2m.h
@@ -3,17 +3,48 @@
 #define ASM__RISCV__P2M_H
 
 #include <xen/errno.h>
+#include <xen/mm.h>
+#include <xen/rwlock.h>
+#include <xen/types.h>
 
 #include <asm/page-bits.h>
 
 #define paddr_bits PADDR_BITS
 
+/* Get host p2m table */
+#define p2m_get_hostp2m(d) (&(d)->arch.p2m)
+
 struct gstage_mode_desc {
     unsigned char mode;
     unsigned int paging_levels;
     char name[8];
 };
 
+/* Per-p2m-table state */
+struct p2m_domain {
+    /*
+     * Lock that protects updates to the p2m.
+     */
+    rwlock_t lock;
+
+    /* Pages used to construct the p2m */
+    struct page_list_head pages;
+
+    /* Back pointer to domain */
+    struct domain *domain;
+
+    /*
+     * P2M updates may required TLBs to be flushed (invalidated).
+     *
+     * Flushes may be deferred by setting 'need_flush' and then flushing
+     * when the p2m write lock is released.
+     *
+     * If an immediate flush is required (e.g, if a super page is
+     * shattered), call p2m_tlb_flush_sync().
+     */
+    bool need_flush;
+};
+
 /*
  * List of possible type for each page in the p2m entry.
  * The number of available bit per page in the pte for this purpose is 2 bits.
@@ -97,6 +128,8 @@ static inline bool arch_acquire_resource_check(struct domain 
*d)
 void guest_mm_init(void);
 unsigned char get_max_supported_mode(void);
 
+int p2m_init(struct domain *d);
+
 #endif /* ASM__RISCV__P2M_H */
 
 /*
diff --git a/xen/arch/riscv/p2m.c b/xen/arch/riscv/p2m.c
index 4e84acaafd..a6e2456f54 100644
--- a/xen/arch/riscv/p2m.c
+++ b/xen/arch/riscv/p2m.c
@@ -3,6 +3,10 @@
 #include <xen/init.h>
 #include <xen/lib.h>
 #include <xen/macros.h>
+#include <xen/mm.h>
+#include <xen/paging.h>
+#include <xen/rwlock.h>
+#include <xen/sched.h>
 #include <xen/sections.h>
 
 #include <asm/csr.h>
@@ -103,3 +107,19 @@ void __init guest_mm_init(void)
      */
     local_hfence_gvma_all();
 }
+
+int p2m_init(struct domain *d)
+{
+    struct p2m_domain *p2m = p2m_get_hostp2m(d);
+
+    /*
+     * "Trivial" initialisation is now complete.  Set the backpointer so the
+     * users of p2m could get an access to domain structure.
+     */
+    p2m->domain = d;
+
+    rwlock_init(&p2m->lock);
+    INIT_PAGE_LIST_HEAD(&p2m->pages);
+
+    return 0;
+}
--
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