KVM: Don't pre-reserve xarray entries when storing empty/NULL attributesgrafted

Skip the xarray reservation loop when clearing all memory attributes, as
storing NULL only erases the entry and never needs to allocate, so no
reservation (and no cleanup of a failed one) is required in that case.

Suggested-by: Sean Christopherson <seanjc@google.com>
Cc: David Ballesteros <davimaba.v@proton.me>
Signed-off-by: Zeng Chi <zengchi@kylinos.cn>
Link: https://patch.msgid.link/20260921102442.1232375-1-zeng_chi911@163.com
[sean: split to separate patch]
Signed-off-by: Sean Christopherson <seanjc@google.com>

1 files changed, 117 insertions, 0 deletions

diff --git a/net/ethtool/debug.c b/net/ethtool/debug.c
new file mode 100644
index 000000000..6043916b4
--- /dev/null
+++ b/net/ethtool/debug.c
@@ -0,0 +1,117 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include "bitset.h"
+#include "common.h"
+#include "netlink.h"
+
+struct debug_req_info {
+	struct ethnl_req_info		base;
+};
+
+struct debug_reply_data {
+	struct ethnl_reply_data		base;
+	u32				msg_mask;
+};
+
+#define DEBUG_REPDATA(__reply_base) \
+	container_of(__reply_base, struct debug_reply_data, base)
+
+const struct nla_policy ethnl_debug_get_policy[] = {
+	[ETHTOOL_A_DEBUG_HEADER]	=
+		NLA_POLICY_NESTED(ethnl_header_policy),
+};
+
+static int debug_prepare_data(const struct ethnl_req_info *req_base,
+			      struct ethnl_reply_data *reply_base,
+			      const struct genl_info *info)
+{
+	struct debug_reply_data *data = DEBUG_REPDATA(reply_base);
+	struct net_device *dev = reply_base->dev;
+	int ret;
+
+	if (!dev->ethtool_ops->get_msglevel)
+		return -EOPNOTSUPP;
+
+	ret = ethnl_ops_begin(dev);
+	if (ret < 0)
+		return ret;
+	data->msg_mask = dev->ethtool_ops->get_msglevel(dev);
+	ethnl_ops_complete(dev);
+
+	return 0;
+}
+
+static int debug_reply_size(const struct ethnl_req_info *req_base,
+			    const struct ethnl_reply_data *reply_base)
+{
+	const struct debug_reply_data *data = DEBUG_REPDATA(reply_base);
+	bool compact = req_base->flags & ETHTOOL_FLAG_COMPACT_BITSETS;
+
+	return ethnl_bitset32_size(&data->msg_mask, NULL, NETIF_MSG_CLASS_COUNT,
+				   netif_msg_class_names, compact);
+}
+
+static int debug_fill_reply(struct sk_buff *skb,
+			    const struct ethnl_req_info *req_base,
+			    const struct ethnl_reply_data *reply_base)
+{
+	const struct debug_reply_data *data = DEBUG_REPDATA(reply_base);
+	bool compact = req_base->flags & ETHTOOL_FLAG_COMPACT_BITSETS;
+
+	return ethnl_put_bitset32(skb, ETHTOOL_A_DEBUG_MSGMASK, &data->msg_mask,
+				  NULL, NETIF_MSG_CLASS_COUNT,
+				  netif_msg_class_names, compact);
+}
+
+/* DEBUG_SET */
+
+const struct nla_policy ethnl_debug_set_policy[] = {
+	[ETHTOOL_A_DEBUG_HEADER]	=
+		NLA_POLICY_NESTED(ethnl_header_policy),
+	[ETHTOOL_A_DEBUG_MSGMASK]	= { .type = NLA_NESTED },
+};
+
+static int
+ethnl_set_debug_validate(struct ethnl_req_info *req_info,
+			 struct genl_info *info)
+{
+	const struct ethtool_ops *ops = req_info->dev->ethtool_ops;
+
+	return ops->get_msglevel && ops->set_msglevel ? 1 : -EOPNOTSUPP;
+}
+
+static int
+ethnl_set_debug(struct ethnl_req_info *req_info, struct genl_info *info)
+{
+	struct net_device *dev = req_info->dev;
+	struct nlattr **tb = info->attrs;
+	bool mod = false;
+	u32 msg_mask;
+	int ret;
+
+	msg_mask = dev->ethtool_ops->get_msglevel(dev);
+	ret = ethnl_update_bitset32(&msg_mask, NETIF_MSG_CLASS_COUNT,
+				    tb[ETHTOOL_A_DEBUG_MSGMASK],
+				    netif_msg_class_names, info->extack, &mod);
+	if (ret < 0 || !mod)
+		return ret;
+
+	dev->ethtool_ops->set_msglevel(dev, msg_mask);
+	return 1;
+}
+
+const struct ethnl_request_ops ethnl_debug_request_ops = {
+	.request_cmd		= ETHTOOL_MSG_DEBUG_GET,
+	.reply_cmd		= ETHTOOL_MSG_DEBUG_GET_REPLY,
+	.hdr_attr		= ETHTOOL_A_DEBUG_HEADER,
+	.req_info_size		= sizeof(struct debug_req_info),
+	.reply_data_size	= sizeof(struct debug_reply_data),
+
+	.prepare_data		= debug_prepare_data,
+	.reply_size		= debug_reply_size,
+	.fill_reply		= debug_fill_reply,
+
+	.set_validate		= ethnl_set_debug_validate,
+	.set			= ethnl_set_debug,
+	.set_ntf_cmd		= ETHTOOL_MSG_DEBUG_NTF,
+};