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

[Jon Doron]

Ah cool did not know about that I will look into it and perhaps can do
a different patchset just for this no need to add it on top of this
patchset

On Wed, May 15, 2019 at 8:48 PM Alex Bennée <address@hidden> wrote:
>
>
> Jon Doron <address@hidden> writes:
>
> > gdb> maint packet qqemu.kvm.Rdmsr:MsrIndex
>
> gdbserver already has a mechanism for exposing system registers see:
>
>   commit 200bf5b7ffea635079cc05fdfb363372b9544ce7
>   Author: Abdallah Bouassida <address@hidden>
>   Date:   Fri May 18 17:48:07 2018 +0100
>
> for an example. As MSR's are very specific to x86 all this should be
> handled via target/i386/gdbstub and kept out of the generic code.
>
> >
> > Signed-off-by: Jon Doron <address@hidden>
> > ---
> >  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[] = {
>
>
> --
> Alex Bennée