From 119e9db233ad0f4cbd4cfb9f9385a7bca378b37d Mon Sep 17 00:00:00 2001
From: Zeng Chi <zengchi@kylinos.cn>
Date: Mon, 21 Sep 2026 18:24:42 +0800
Subject: KVM: Don't pre-reserve xarray entries when storing empty/NULL
 attributes

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>
---
 drivers/scsi/sd_dif.c | 73 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 73 insertions(+)
 create mode 100644 drivers/scsi/sd_dif.c

(limited to 'drivers/scsi/sd_dif.c')

diff --git a/drivers/scsi/sd_dif.c b/drivers/scsi/sd_dif.c
new file mode 100644
index 000000000..ff4217fef
--- /dev/null
+++ b/drivers/scsi/sd_dif.c
@@ -0,0 +1,73 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * sd_dif.c - SCSI Data Integrity Field
+ *
+ * Copyright (C) 2007, 2008 Oracle Corporation
+ * Written by: Martin K. Petersen <martin.petersen@oracle.com>
+ */
+
+#include <linux/blk-integrity.h>
+#include <linux/t10-pi.h>
+
+#include <scsi/scsi.h>
+#include <scsi/scsi_cmnd.h>
+#include <scsi/scsi_dbg.h>
+#include <scsi/scsi_device.h>
+#include <scsi/scsi_driver.h>
+#include <scsi/scsi_eh.h>
+#include <scsi/scsi_host.h>
+#include <scsi/scsi_ioctl.h>
+#include <scsi/scsicam.h>
+
+#include "sd.h"
+
+/*
+ * Configure exchange of protection information between OS and HBA.
+ */
+void sd_dif_config_host(struct scsi_disk *sdkp, struct queue_limits *lim)
+{
+	struct scsi_device *sdp = sdkp->device;
+	u8 type = sdkp->protection_type;
+	struct blk_integrity *bi = &lim->integrity;
+	int dif, dix;
+
+	memset(bi, 0, sizeof(*bi));
+
+	dif = scsi_host_dif_capable(sdp->host, type);
+	dix = scsi_host_dix_capable(sdp->host, type);
+
+	if (!dix && scsi_host_dix_capable(sdp->host, 0)) {
+		dif = 0; dix = 1;
+	}
+
+	if (!dix)
+		return;
+
+	/* Enable DMA of protection information */
+	if (scsi_host_get_guard(sdkp->device->host) & SHOST_DIX_GUARD_IP)
+		bi->csum_type = BLK_INTEGRITY_CSUM_IP;
+	else
+		bi->csum_type = BLK_INTEGRITY_CSUM_CRC;
+
+	if (type != T10_PI_TYPE3_PROTECTION)
+		bi->flags |= BLK_INTEGRITY_REF_TAG;
+
+	bi->metadata_size = sizeof(struct t10_pi_tuple);
+	bi->pi_tuple_size = bi->metadata_size;
+
+	if (dif && type) {
+		bi->flags |= BLK_INTEGRITY_DEVICE_CAPABLE;
+
+		if (!sdkp->ATO)
+			return;
+
+		if (type == T10_PI_TYPE3_PROTECTION)
+			bi->tag_size = sizeof(u16) + sizeof(u32);
+		else
+			bi->tag_size = sizeof(u16);
+	}
+
+	sd_first_printk(KERN_NOTICE, sdkp,
+			"Enabling DIX %s, application tag size %u bytes\n",
+			blk_integrity_profile_name(bi), bi->tag_size);
+}
-- 
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