[Qemu-devel] [PATCH v9 26/27] gdbstub: Add support to read a MSR for KVM target

[Jon Doron <arilou@gmail.com>]

gdb> maint packet qqemu.kvm.Rdmsr:MsrIndex

Signed-off-by: Jon Doron <arilou@gmail.com>
---
 gdbstub.c | 38 +++++++++++++++++++++++++++++++++++++-
 1 file changed, 37 insertions(+), 1 deletion(-)

diff --git a/gdbstub.c b/gdbstub.c
index 34da10260d..f48c3a2b5f 100644
--- a/gdbstub.c
+++ b/gdbstub.c
@@ -2141,7 +2141,14 @@ static void handle_query_attached(GdbCmdContext *gdb_ctx, void *user_ctx)
 
 static void handle_query_qemu_supported(GdbCmdContext *gdb_ctx, void *user_ctx)
 {
-    put_packet(gdb_ctx->s, "sstepbits;sstep;PhyMemMode");
+    snprintf(gdb_ctx->str_buf, sizeof(gdb_ctx->str_buf),
+             "sstepbits;sstep;PhyMemMode");
+
+    if (kvm_enabled()) {
+        pstrcat(gdb_ctx->str_buf, sizeof(gdb_ctx->str_buf), ";kvm.Rdmsr");
+    }
+
+    put_packet(gdb_ctx->s, gdb_ctx->str_buf);
 }
 
 static void handle_query_qemu_phy_mem_mode(GdbCmdContext *gdb_ctx,
@@ -2166,6 +2173,29 @@ static void handle_set_qemu_phy_mem_mode(GdbCmdContext *gdb_ctx, void *user_ctx)
     put_packet(gdb_ctx->s, "OK");
 }
 
+static void handle_query_kvm_read_msr(GdbCmdContext *gdb_ctx, void *user_ctx)
+{
+    uint64_t msr_val;
+
+    if (!kvm_enabled()) {
+        return;
+    }
+
+    if (!gdb_ctx->num_params) {
+        put_packet(gdb_ctx->s, "E22");
+        return;
+    }
+
+    if (kvm_arch_read_msr(gdbserver_state->c_cpu, gdb_ctx->params[0].val_ul,
+                          &msr_val)) {
+        put_packet(gdb_ctx->s, "E00");
+        return;
+    }
+
+    snprintf(gdb_ctx->str_buf, sizeof(gdb_ctx->str_buf), "0x%" PRIx64, msr_val);
+    put_packet(gdb_ctx->s, gdb_ctx->str_buf);
+}
+
 static GdbCmdParseEntry gdb_gen_query_set_common_table[] = {
     /* Order is important if has same prefix */
     {
@@ -2250,6 +2280,12 @@ static GdbCmdParseEntry gdb_gen_query_table[] = {
         .handler = handle_query_qemu_phy_mem_mode,
         .cmd = "qemu.PhyMemMode",
     },
+    {
+        .handler = handle_query_kvm_read_msr,
+        .cmd = "qemu.kvm.Rdmsr:",
+        .cmd_startswith = 1,
+        .schema = "l0"
+    },
 };
 
 static GdbCmdParseEntry gdb_gen_set_table[] = {
-- 
2.20.1