Re: [PATCH v2 5/8] xen/riscv: introduce asm/pmap.h header

[Julien Grall]

Hi Oleksii,

On 12/07/2024 17:22, Oleksii Kurochko wrote:

Introduces arch_pmap_{un}map functions and select HAS_PMAP
for CONFIG_RISCV.

Additionaly it was necessary to introduce functions:
  - mfn_to_xen_entry
  - mfn_to_pte

Signed-off-by: Oleksii Kurochko <oleksii.kuroc...@gmail.com>
---
Changes in V2:
  - newly introduced patch
---
  xen/arch/riscv/Kconfig            |  1 +
  xen/arch/riscv/include/asm/page.h |  2 ++
  xen/arch/riscv/include/asm/pmap.h | 28 ++++++++++++++++++++++++++++
  xen/arch/riscv/mm.c               | 14 ++++++++++++++
  4 files changed, 45 insertions(+)
  create mode 100644 xen/arch/riscv/include/asm/pmap.h

diff --git a/xen/arch/riscv/Kconfig b/xen/arch/riscv/Kconfig
index 259eea8d3b..0112aa8778 100644
--- a/xen/arch/riscv/Kconfig
+++ b/xen/arch/riscv/Kconfig
@@ -3,6 +3,7 @@ config RISCV
        select FUNCTION_ALIGNMENT_16B
        select GENERIC_BUG_FRAME
        select HAS_DEVICE_TREE
+       select HAS_PMAP

config RISCV_64

        def_bool y
diff --git a/xen/arch/riscv/include/asm/page.h 
b/xen/arch/riscv/include/asm/page.h
index cbbf3656d1..339074d502 100644
--- a/xen/arch/riscv/include/asm/page.h
+++ b/xen/arch/riscv/include/asm/page.h
@@ -51,6 +51,8 @@ typedef struct {
  #endif
  } pte_t;

+pte_t mfn_to_xen_entry(mfn_t mfn, unsigned int attr);

+
  static inline pte_t paddr_to_pte(paddr_t paddr,
                                   unsigned int permissions)
  {
diff --git a/xen/arch/riscv/include/asm/pmap.h 
b/xen/arch/riscv/include/asm/pmap.h
new file mode 100644
index 0000000000..eb4c48515c
--- /dev/null
+++ b/xen/arch/riscv/include/asm/pmap.h
@@ -0,0 +1,28 @@
+#ifndef __ASM_PMAP_H__
+#define __ASM_PMAP_H__
+
+#include <xen/bug.h>
+#include <xen/mm.h>
+
+#include <asm/fixmap.h>
+
+static inline void arch_pmap_map(unsigned int slot, mfn_t mfn)
+{
+    pte_t *entry = &xen_fixmap[slot];
+    pte_t pte;
+
+    ASSERT(!pte_is_valid(*entry));
+
+    pte = mfn_to_xen_entry(mfn, PAGE_HYPERVISOR_RW);
+    pte.pte |= PTE_LEAF_DEFAULT;
+    write_pte(entry, pte);
+}
+
+static inline void arch_pmap_unmap(unsigned int slot)
+{
+    pte_t pte = {};
+
+    write_pte(&xen_fixmap[slot], pte);
+}
+
+#endif /* __ASM_PMAP_H__ */
diff --git a/xen/arch/riscv/mm.c b/xen/arch/riscv/mm.c
index d69a174b5d..445319af08 100644
--- a/xen/arch/riscv/mm.c
+++ b/xen/arch/riscv/mm.c
@@ -370,3 +370,17 @@ int map_pages_to_xen(unsigned long virt,
      BUG_ON("unimplemented");
      return -1;
  }
+
+static inline pte_t mfn_to_pte(mfn_t mfn)
+{
+    unsigned long pte = mfn_x(mfn) << PTE_PPN_SHIFT;
+    return (pte_t){ .pte = pte};
+}
+
+inline pte_t mfn_to_xen_entry(mfn_t mfn, unsigned int attr)
+{
+    /* there is no attr field in RISC-V's pte */
+    (void) attr;

Surely you have a way to say indicate whether an entry is readable/writable?

+
+    return mfn_to_pte(mfn);
+}

Cheers,

--
Julien Grall