[PATCH 3/3] cxl: Add support for device sanitation

[Davidlohr Bueso <dave@stgolabs.net>]

Make use of the background operations through the sanitize
command, per CXL 3.0 specs. Traditionally run times can be
rather long, depending on the size of the media.

Estimate times based on:
	 https://pmem.io/documents/NVDIMM_DSM_Interface-V1.8.pdf

Signed-off-by: Davidlohr Bueso <dave@stgolabs.net>
---
 hw/cxl/cxl-mailbox-utils.c  | 139 +++++++++++++++++++++++++++++++++++-
 hw/mem/cxl_type3.c          |   9 ++-
 include/hw/cxl/cxl_device.h |  17 +++++
 3 files changed, 162 insertions(+), 3 deletions(-)

diff --git a/hw/cxl/cxl-mailbox-utils.c b/hw/cxl/cxl-mailbox-utils.c
index 61f0b8d675bc..aa0641f786e2 100644
--- a/hw/cxl/cxl-mailbox-utils.c
+++ b/hw/cxl/cxl-mailbox-utils.c
@@ -18,6 +18,7 @@
 #include "qemu/log.h"
 #include "qemu/units.h"
 #include "qemu/uuid.h"
+#include "sysemu/hostmem.h"
 
 #define CXL_CAPACITY_MULTIPLIER   (256 * MiB)
 
@@ -71,6 +72,9 @@ enum {
         #define GET_PARTITION_INFO     0x0
         #define GET_LSA       0x2
         #define SET_LSA       0x3
+    SANITIZE    = 0x44,
+        #define OVERWRITE     0x0
+        #define SECURE_ERASE  0x1
     MEDIA_AND_POISON = 0x43,
         #define GET_POISON_LIST        0x0
         #define INJECT_POISON          0x1
@@ -626,6 +630,109 @@ static CXLRetCode cmd_ccls_set_lsa(struct cxl_cmd *cmd,
     return CXL_MBOX_SUCCESS;
 }
 
+/* Perform the actual device zeroing */
+static void __do_sanitization(CXLDeviceState *cxl_dstate)
+{
+    MemoryRegion *mr;
+    CXLType3Dev *ct3d = container_of(cxl_dstate, CXLType3Dev, cxl_dstate);
+
+    if (ct3d->hostvmem) {
+        mr = host_memory_backend_get_memory(ct3d->hostvmem);
+        if (mr) {
+            void *hostmem = memory_region_get_ram_ptr(mr);
+            memset(hostmem, 0, memory_region_size(mr));
+        }
+    }
+
+    if (ct3d->hostpmem) {
+        mr = host_memory_backend_get_memory(ct3d->hostpmem);
+        if (mr) {
+            void *hostmem = memory_region_get_ram_ptr(mr);
+            memset(hostmem, 0, memory_region_size(mr));
+        }
+    }
+    if (ct3d->lsa) {
+        mr = host_memory_backend_get_memory(ct3d->lsa);
+        if (mr) {
+            void *lsa = memory_region_get_ram_ptr(mr);
+            memset(lsa, 0, memory_region_size(mr));
+        }
+    }
+}
+
+/*
+ * CXL 3.0 spec section 8.2.9.8.5.1 - Sanitize.
+ *
+ * Once the Sanitize command has started successfully, the device shall be
+ * placed in the media disabled state. If the command fails or is interrupted
+ * by a reset or power failure, it shall remain in the media disabled state
+ * until a successful Sanitize command has been completed. During this state:
+ *
+ * 1. Memory writes to the device will have no effect, and all memory reads
+ * will return random values (no user data returned, even for locations that
+ * the failed Sanitize operation didn’t sanitize yet).
+ *
+ * 2. Mailbox commands shall still be processed in the disabled state, except
+ * that commands that access Sanitized areas shall fail with the Media Disabled
+ * error code.
+ */
+static CXLRetCode cmd_sanitize_overwrite(struct cxl_cmd *cmd,
+                                         CXLDeviceState *cxl_dstate,
+                                         uint16_t *len)
+{
+    uint64_t total_mem; /* in Mb */
+    int secs;
+
+    total_mem = (cxl_dstate->vmem_size + cxl_dstate->pmem_size) >> 20;
+    if (total_mem <= 512) {
+        secs = 4;
+    } else if (total_mem <= 1024) {
+        secs = 8;
+    } else if (total_mem <= 2 * 1024) {
+        secs = 15;
+    } else if (total_mem <= 4 * 1024) {
+        secs = 30;
+    } else if (total_mem <= 8 * 1024) {
+        secs = 60;
+    } else if (total_mem <= 16 * 1024) {
+        secs = 2 * 60;
+    } else if (total_mem <= 32 * 1024) {
+        secs = 4 * 60;
+    } else if (total_mem <= 64 * 1024) {
+        secs = 8 * 60;
+    } else if (total_mem <= 128 * 1024) {
+        secs = 15 * 60;
+    } else if (total_mem <= 256 * 1024) {
+        secs = 30 * 60;
+    } else if (total_mem <= 512 * 1024) {
+        secs = 60 * 60;
+    } else if (total_mem <= 1024 * 1024) {
+        secs = 120 * 60;
+    } else {
+        secs = 240 * 60; /* max 4 hrs */
+    }
+
+    /* EBUSY other bg cmds as of now */
+    cxl_dstate->bg.runtime = secs * 1000UL;
+    *len = 0;
+
+    qemu_log_mask(LOG_UNIMP,
+                  "Sanitize/overwrite command runtime for %ldMb media: %d seconds\n",
+                  total_mem, secs);
+
+    cxl_dev_disable_media(cxl_dstate);
+
+    if (secs > 2) {
+        /* sanitize when done */
+        return CXL_MBOX_BG_STARTED;
+    } else {
+        __do_sanitization(cxl_dstate);
+        cxl_dev_enable_media(cxl_dstate);
+
+        return CXL_MBOX_SUCCESS;
+    }
+}
+
 /*
  * This is very inefficient, but good enough for now!
  * Also the payload will always fit, so no need to handle the MORE flag and
@@ -843,6 +950,8 @@ static struct cxl_cmd cxl_cmd_set[256][256] = {
     [CCLS][GET_LSA] = { "CCLS_GET_LSA", cmd_ccls_get_lsa, 8, 0 },
     [CCLS][SET_LSA] = { "CCLS_SET_LSA", cmd_ccls_set_lsa,
         ~0, IMMEDIATE_CONFIG_CHANGE | IMMEDIATE_DATA_CHANGE },
+    [SANITIZE][OVERWRITE] = { "SANITIZE_OVERWRITE", cmd_sanitize_overwrite,
+        0, IMMEDIATE_DATA_CHANGE | SECURITY_STATE_CHANGE | BACKGROUND_OPERATION },
     [MEDIA_AND_POISON][GET_POISON_LIST] = { "MEDIA_AND_POISON_GET_POISON_LIST",
         cmd_media_get_poison_list, 16, 0 },
     [MEDIA_AND_POISON][INJECT_POISON] = { "MEDIA_AND_POISON_INJECT_POISON",
@@ -898,6 +1007,21 @@ void cxl_process_mailbox(CXLDeviceState *cxl_dstate)
                     ret = CXL_MBOX_BUSY;
                     goto done;
             }
+            /* forbid any selected commands while overwriting */
+            if (sanitize_running(cxl_dstate)) {
+                if (h == cmd_events_get_records ||
+                    h == cmd_ccls_get_partition_info ||
+                    h == cmd_ccls_set_lsa ||
+                    h == cmd_ccls_get_lsa ||
+                    h == cmd_logs_get_log ||
+                    h == cmd_media_get_poison_list ||
+                    h == cmd_media_inject_poison ||
+                    h == cmd_media_clear_poison ||
+                    h == cmd_sanitize_overwrite) {
+                        ret = CXL_MBOX_MEDIA_DISABLED;
+                        goto done;
+                }
+            }
             ret = (*h)(cxl_cmd, cxl_dstate, &len);
             if ((cxl_cmd->effect & BACKGROUND_OPERATION) &&
                 ret == CXL_MBOX_BG_STARTED) {
@@ -970,8 +1094,19 @@ static void bg_timercb(void *opaque)
 
         bg_status_reg = FIELD_DP64(bg_status_reg, CXL_DEV_BG_CMD_STS, RET_CODE, ret);
 
-        /* TODO add ad-hoc cmd succesful completion handling */
-
+        if (ret == CXL_MBOX_SUCCESS) {
+            switch (cxl_dstate->bg.opcode) {
+            case 0x4400: /* sanitize */
+                __do_sanitization(cxl_dstate);
+                cxl_dev_enable_media(cxl_dstate);
+                break;
+            case 0x4304: /* TODO: scan media */
+                break;
+            default:
+                __builtin_unreachable();
+                break;
+            }
+        }
         qemu_log("Background command %04xh finished: %s\n",
                  cxl_dstate->bg.opcode,
                  ret == CXL_MBOX_SUCCESS ? "success" : "aborted");
diff --git a/hw/mem/cxl_type3.c b/hw/mem/cxl_type3.c
index 334ce92f5e0f..2b483d3d8ea9 100644
--- a/hw/mem/cxl_type3.c
+++ b/hw/mem/cxl_type3.c
@@ -12,6 +12,7 @@
 #include "qemu/pmem.h"
 #include "qemu/range.h"
 #include "qemu/rcu.h"
+#include "qemu/guest-random.h"
 #include "sysemu/hostmem.h"
 #include "sysemu/numa.h"
 #include "hw/cxl/cxl.h"
@@ -988,6 +989,10 @@ MemTxResult cxl_type3_read(PCIDevice *d, hwaddr host_addr, uint64_t *data,
         return MEMTX_ERROR;
     }
 
+    if (sanitize_running(&CXL_TYPE3(d)->cxl_dstate)) {
+        qemu_guest_getrandom_nofail(data, size);
+        return MEMTX_OK;
+    }
     return address_space_read(as, dpa_offset, attrs, data, size);
 }
 
@@ -1003,7 +1008,9 @@ MemTxResult cxl_type3_write(PCIDevice *d, hwaddr host_addr, uint64_t data,
     if (res) {
         return MEMTX_ERROR;
     }
-
+    if (sanitize_running(&CXL_TYPE3(d)->cxl_dstate)) {
+        return MEMTX_OK;
+    }
     return address_space_write(as, dpa_offset, attrs, &data, size);
 }
 
diff --git a/include/hw/cxl/cxl_device.h b/include/hw/cxl/cxl_device.h
index f986651b6ead..e28536969397 100644
--- a/include/hw/cxl/cxl_device.h
+++ b/include/hw/cxl/cxl_device.h
@@ -346,6 +346,23 @@ REG64(CXL_MEM_DEV_STS, 0)
     FIELD(CXL_MEM_DEV_STS, MBOX_READY, 4, 1)
     FIELD(CXL_MEM_DEV_STS, RESET_NEEDED, 5, 3)
 
+static inline void __toggle_media(CXLDeviceState *cxl_dstate, int val)
+{
+    uint64_t dev_status_reg;
+
+    dev_status_reg = FIELD_DP64(0, CXL_MEM_DEV_STS, MEDIA_STATUS, val);
+    cxl_dstate->mbox_reg_state64[R_CXL_MEM_DEV_STS] = dev_status_reg;
+}
+#define cxl_dev_disable_media(cxlds)                    \
+        do { __toggle_media((cxlds), 0x3); } while (0)
+#define cxl_dev_enable_media(cxlds)                     \
+        do { __toggle_media((cxlds), 0x1); } while (0)
+
+static inline bool sanitize_running(CXLDeviceState *cxl_dstate)
+{
+    return !!cxl_dstate->bg.runtime && cxl_dstate->bg.opcode == 0x4400;
+}
+
 typedef struct CXLError {
     QTAILQ_ENTRY(CXLError) node;
     int type; /* Error code as per FE definition */
-- 
2.39.2