On 1/27/25 11:09 AM, Jan Beulich wrote:
On 20.01.2025 17:54, Oleksii Kurochko wrote:
vmap_to_mfn() uses virt_to_maddr(), which is designed to work with VA from
either the direct map region or Xen's linkage region (XEN_VIRT_START).
An assertion will occur if it is used with other regions, in particular for
the VMAP region.
Since RISC-V lacks a hardware feature to request the MMU to translate a VA to
a PA (as Arm does, for example), software page table walking (pt_walk()) is
used for the VMAP region to obtain the PA.
Fixes: 7db8d2bd9b ("xen/riscv: add minimal stuff to mm.h to build full Xen")
Signed-off-by: Oleksii Kurochko<oleksii.kuroc...@gmail.com>
Reviewed-by: Jan Beulich<jbeul...@suse.com>
--- a/xen/arch/riscv/include/asm/mm.h
+++ b/xen/arch/riscv/include/asm/mm.h
@@ -25,7 +25,7 @@ paddr_t pt_walk(vaddr_t va);
#define gaddr_to_gfn(ga) _gfn(paddr_to_pfn(ga))
#define mfn_to_maddr(mfn) pfn_to_paddr(mfn_x(mfn))
#define maddr_to_mfn(ma) _mfn(paddr_to_pfn(ma))
-#define vmap_to_mfn(va) maddr_to_mfn(virt_to_maddr((vaddr_t)(va)))
+#define vmap_to_mfn(va) maddr_to_mfn(pt_walk((vaddr_t)(va)))
With this being the first use of pt_walk(), I wonder whether the function might
better return mfn_t (and simply ignore the low 12 bits of Vthe incoming VA; see
my respective comment on the earlier patch). After all it is quite natural for
a page table walk to return a page frame number, not a physical address.
I think it would be really better to return mfn_t (now I understand your
comment on the earlier
patch better,if only I had read this comment first...)
Thanks.
~ Oleksii
