Improve debugability of VMware Linux guests by dumping
kernel messages during a panic to VM log file (vmware.log).
Co-developed-by: Bo Gan <bo.gan@xxxxxxxxxxxx>
Signed-off-by: Bo Gan <bo.gan@xxxxxxxxxxxx>
Signed-off-by: Alexey Makhalov <alexey.makhalov@xxxxxxxxxxxx>
---
arch/x86/include/asm/vmware.h | 1 +
arch/x86/kernel/cpu/vmware.c | 132 ++++++++++++++++++++++++++++++++++
2 files changed, 133 insertions(+)
diff --git a/arch/x86/include/asm/vmware.h b/arch/x86/include/asm/vmware.h
index c9cf43d5ef23..433755b41a27 100644
--- a/arch/x86/include/asm/vmware.h
+++ b/arch/x86/include/asm/vmware.h
@@ -57,6 +57,7 @@
#define VMWARE_HYPERVISOR_MAGIC 0x564d5868U
#define VMWARE_CMD_GETVERSION 10
+#define VMWARE_CMD_MESSAGE 30
#define VMWARE_CMD_GETHZ 45
#define VMWARE_CMD_GETVCPU_INFO 68
#define VMWARE_CMD_STEALCLOCK 91
diff --git a/arch/x86/kernel/cpu/vmware.c b/arch/x86/kernel/cpu/vmware.c
index 00189cdeb775..9883766715fe 100644
--- a/arch/x86/kernel/cpu/vmware.c
+++ b/arch/x86/kernel/cpu/vmware.c
@@ -28,6 +28,7 @@
#include <linux/cpu.h>
#include <linux/reboot.h>
#include <linux/static_call.h>
+#include <linux/kmsg_dump.h>
#include <asm/div64.h>
#include <asm/x86_init.h>
#include <asm/hypervisor.h>
@@ -139,6 +140,13 @@ static unsigned long vmware_get_tsc_khz(void)
return vmware_tsc_khz;
}
+static void kmsg_dumper_vmware_log(struct kmsg_dumper *dumper,
+ enum kmsg_dump_reason reason);
+
+static struct kmsg_dumper kmsg_dumper = {
+ .dump = kmsg_dumper_vmware_log
+};
+
#ifdef CONFIG_PARAVIRT
static struct cyc2ns_data vmware_cyc2ns __ro_after_init;
static bool vmw_sched_clock __initdata = true;
@@ -436,6 +444,8 @@ static void __init vmware_platform_setup(void)
#endif
vmware_set_capabilities();
+
+ kmsg_dump_register(&kmsg_dumper);
}
static u8 __init vmware_select_hypercall(void)
@@ -587,3 +597,125 @@ const __initconst struct hypervisor_x86 x86_hyper_vmware = {
.runtime.sev_es_hcall_finish = vmware_sev_es_hcall_finish,
#endif
};
+
+#define VMWARE_HB_CMD_MESSAGE 0
+#define MESSAGE_STATUS_SUCCESS (0x01 << 16)
+#define MESSAGE_STATUS_CPT (0x10 << 16)
+#define MESSAGE_STATUS_HB (0x80 << 16)
+
+#define RPCI_PROTOCOL_NUM 0x49435052 /* 'RPCI' */
+#define GUESTMSG_FLAG_COOKIE 0x80000000
+
+#define MESSAGE_TYPE_OPEN (0 << 16)
+#define MESSAGE_TYPE_SENDSIZE (1 << 16)
+#define MESSAGE_TYPE_SEND (2 << 16)
+#define MESSAGE_TYPE_CLOSE (6 << 16)
+
+struct vmw_msg {
+ u32 id;
+ u32 cookie_high;
+ u32 cookie_low;
+};
+
+static int
+vmware_log_open(struct vmw_msg *msg)
+{
+ u32 info;
+
+ vmware_hypercall6(VMWARE_CMD_MESSAGE | MESSAGE_TYPE_OPEN,
+ RPCI_PROTOCOL_NUM | GUESTMSG_FLAG_COOKIE,
+ 0, &info, &msg->id, &msg->cookie_high,
+ &msg->cookie_low);
+
+ if ((info & MESSAGE_STATUS_SUCCESS) == 0)
+ return 1;
+
+ msg->id &= 0xffff0000UL;
+ return 0;
+}
+
+static int
+vmware_log_close(struct vmw_msg *msg)
+{
+ u32 info;
+
+ vmware_hypercall5(VMWARE_CMD_MESSAGE | MESSAGE_TYPE_CLOSE, 0, msg->id,
+ msg->cookie_high, msg->cookie_low, &info);
+
+ if ((info & MESSAGE_STATUS_SUCCESS) == 0)
+ return 1;
+ return 0;
+}
+
+static int
+vmware_log_send(struct vmw_msg *msg, const char *string)
+{
+ u32 info;
+ u32 len = strlen(string);
+
+retry:
+ vmware_hypercall5(VMWARE_CMD_MESSAGE | MESSAGE_TYPE_SENDSIZE, len,
+ msg->id, msg->cookie_high, msg->cookie_low, &info);
+
+ if (!(info & MESSAGE_STATUS_SUCCESS))
+ return 1;
+
+ /* HB port can't access encrypted memory. */
+ if (!cc_platform_has(CC_ATTR_MEM_ENCRYPT) && (info & MESSAGE_STATUS_HB)) {
+ vmware_hypercall_hb_out(
+ VMWARE_HB_CMD_MESSAGE | MESSAGE_STATUS_SUCCESS,
+ len, msg->id, (uintptr_t) string, msg->cookie_low,
+ msg->cookie_high, &info);
+ } else {
+ do {
+ u32 word;
+ size_t s = min_t(u32, len, sizeof(word));
+
+ memcpy(&word, string, s);
+ len -= s;
+ string += s;
+
+ vmware_hypercall5(VMWARE_CMD_MESSAGE | MESSAGE_TYPE_SEND,
+ word, msg->id, msg->cookie_high,
+ msg->cookie_low, &info);
+ } while (len && (info & MESSAGE_STATUS_SUCCESS));
+ }
+
+ if ((info & MESSAGE_STATUS_SUCCESS) == 0) {
+ if (info & MESSAGE_STATUS_CPT)
+ /* A checkpoint occurred. Retry. */
+ goto retry;
+ return 1;
+ }
+ return 0;
+}
+STACK_FRAME_NON_STANDARD(vmware_log_send);
+
+/**
+ * kmsg_dumper_vmware_log - dumps kmsg to vmware.log file on the host
+ */
+static void kmsg_dumper_vmware_log(struct kmsg_dumper *dumper,
+ enum kmsg_dump_reason reason)
+{
+ struct vmw_msg msg;
+ struct kmsg_dump_iter iter;
+ static char line[1024];
+ size_t len = 0;
+
+ /* Line prefix to send to VM log file. */
+ line[0] = 'l';
+ line[1] = 'o';
+ line[2] = 'g';
+ line[3] = ' ';
+
+ kmsg_dump_rewind(&iter);
+ while (kmsg_dump_get_line(&iter, true, line + 4, sizeof(line) - 4,
+ &len)) {
+ line[len + 4] = '\0';
+ if (vmware_log_open(&msg))
+ return;
+ if (vmware_log_send(&msg, line))
+ return;
+ vmware_log_close(&msg);
+ }
+}
--
2.39.4
