Mailing List Archive

[xen master] xen/x86: Use ASSERT instead of VIRTUAL_BUG_ON for phys_to_nid
commit e9c72d524fbdb109c45f24acce998f0bd552fb6f
Author: Wei Chen <>
AuthorDate: Mon Dec 12 12:13:26 2022 +0100
Commit: Jan Beulich <>
CommitDate: Mon Dec 12 12:13:26 2022 +0100

xen/x86: Use ASSERT instead of VIRTUAL_BUG_ON for phys_to_nid

VIRTUAL_BUG_ON is an empty macro used in phys_to_nid. This
results in two lines of error-checking code in phys_to_nid
that is not actually working and causing two compilation
1. error: "MAX_NUMNODES" undeclared (first use in this function).
This is because in the common header file, "MAX_NUMNODES" is
defined after the common header file includes the ARCH header
file, where phys_to_nid has attempted to use "MAX_NUMNODES".
This error was resolved after we moved the phys_to_nid from
x86 ARCH header file to common header file.
2. error: wrong type argument to unary exclamation mark.
This is because, the error-checking code contains !node_data[nid].
But node_data is a data structure variable, it's not a pointer.

So, in this patch, we use ASSERT instead of VIRTUAL_BUG_ON to
enable the two lines of error-checking code. And fix the left
compilation errors by replacing !node_data[nid] to
!node_data[nid].node_spanned_pages. Although NUMA allows one node
can only have CPUs but without any memory. And node with 0 bytes
of memory might have an entry in memnodemap[] theoretically. But
that doesn't mean phys_to_nid can find any valid address from a
node with 0 bytes memory.

Signed-off-by: Wei Chen <>
Tested-by: Jiamei Xie <>
Acked-by: Jan Beulich <>
xen/include/xen/numa.h | 6 ++----
1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/xen/include/xen/numa.h b/xen/include/xen/numa.h
index 5b3877344b..04556f3a6f 100644
--- a/xen/include/xen/numa.h
+++ b/xen/include/xen/numa.h
@@ -35,8 +35,6 @@ struct node {
extern int compute_hash_shift(const struct node *nodes,
unsigned int numnodes, const nodeid_t *nodeids);

-#define VIRTUAL_BUG_ON(x)
extern bool numa_off;

extern void numa_add_cpu(unsigned int cpu);
@@ -69,9 +67,9 @@ extern struct node_data node_data[];
static inline nodeid_t __attribute_pure__ phys_to_nid(paddr_t addr)
nodeid_t nid;
- VIRTUAL_BUG_ON((paddr_to_pdx(addr) >> memnode_shift) >= memnodemapsize);
+ ASSERT((paddr_to_pdx(addr) >> memnode_shift) < memnodemapsize);
nid = memnodemap[paddr_to_pdx(addr) >> memnode_shift];
- VIRTUAL_BUG_ON(nid >= MAX_NUMNODES || !node_data[nid]);
+ ASSERT(nid < MAX_NUMNODES && node_data[nid].node_spanned_pages);
return nid;

generated by git-patchbot for /home/xen/git/xen.git#master