Re: [Qemu-devel] [Qemu devel v6 PATCH 2/5] msf2: Microsemi Smartfusion2 System Register block.

[sundeep subbaraya]

Hi Alistair,

On Fri, Jul 7, 2017 at 10:03 PM, Alistair Francis <address@hidden>
wrote:

> On Fri, Jul 7, 2017 at 12:08 AM, sundeep subbaraya
> <address@hidden> wrote:
> > Hi Alistair,
> >
> > On Wed, Jul 5, 2017 at 11:36 PM, Alistair Francis <address@hidden>
> > wrote:
> >>
> >> On Sun, Jul 2, 2017 at 9:45 PM, Subbaraya Sundeep
> >> <address@hidden> wrote:
> >> > Added Sytem register block of Smartfusion2.
> >> > This block has PLL registers which are accessed by guest.
> >> >
> >> > Signed-off-by: Subbaraya Sundeep <address@hidden>
> >> > ---
> >> >  hw/misc/Makefile.objs         |   1 +
> >> >  hw/misc/msf2-sysreg.c         | 200
> >> > ++++++++++++++++++++++++++++++++++++++++++
> >> >  include/hw/misc/msf2-sysreg.h |  82 +++++++++++++++++
> >> >  3 files changed, 283 insertions(+)
> >> >  create mode 100644 hw/misc/msf2-sysreg.c
> >> >  create mode 100644 include/hw/misc/msf2-sysreg.h
> >> >
> >> > diff --git a/hw/misc/Makefile.objs b/hw/misc/Makefile.objs
> >> > index c8b4893..0f52354 100644
> >> > --- a/hw/misc/Makefile.objs
> >> > +++ b/hw/misc/Makefile.objs
> >> > @@ -56,3 +56,4 @@ obj-$(CONFIG_EDU) += edu.o
> >> >  obj-$(CONFIG_HYPERV_TESTDEV) += hyperv_testdev.o
> >> >  obj-$(CONFIG_AUX) += auxbus.o
> >> >  obj-$(CONFIG_ASPEED_SOC) += aspeed_scu.o aspeed_sdmc.o
> >> > +obj-$(CONFIG_MSF2) += msf2-sysreg.o
> >> > diff --git a/hw/misc/msf2-sysreg.c b/hw/misc/msf2-sysreg.c
> >> > new file mode 100644
> >> > index 0000000..64ee141
> >> > --- /dev/null
> >> > +++ b/hw/misc/msf2-sysreg.c
> >> > @@ -0,0 +1,200 @@
> >> > +/*
> >> > + * System Register block model of Microsemi SmartFusion2.
> >> > + *
> >> > + * Copyright (c) 2017 Subbaraya Sundeep <address@hidden>
> >> > + *
> >> > + * This program is free software; you can redistribute it and/or
> >> > + * modify it under the terms of the GNU General Public License
> >> > + * as published by the Free Software Foundation; either version
> >> > + * 2 of the License, or (at your option) any later version.
> >> > + *
> >> > + * You should have received a copy of the GNU General Public License
> >> > along
> >> > + * with this program; if not, see <http://www.gnu.org/licenses/>.
> >> > + */
> >> > +
> >> > +#include "hw/misc/msf2-sysreg.h"
> >>
> >> Same #include comment from patch 1.
> >
> >
> > Ok will change.
> >>
> >>
> >> > +
> >> > +#ifndef MSF2_SYSREG_ERR_DEBUG
> >> > +#define MSF2_SYSREG_ERR_DEBUG  0
> >> > +#endif
> >> > +
> >> > +#define DB_PRINT_L(lvl, fmt, args...) do { \
> >> > +    if (MSF2_SYSREG_ERR_DEBUG >= lvl) { \
> >> > +        qemu_log("%s: " fmt "\n", __func__, ## args); \
> >> > +    } \
> >> > +} while (0);
> >> > +
> >> > +#define DB_PRINT(fmt, args...) DB_PRINT_L(1, fmt, ## args)
> >> > +
> >> > +static inline int msf2_divbits(uint32_t div)
> >> > +{
> >> > +    int ret = 0;
> >> > +
> >> > +    switch (div) {
> >> > +    case 1:
> >> > +        ret = 0;
> >> > +        break;
> >> > +    case 2:
> >> > +        ret = 1;
> >> > +        break;
> >> > +    case 4:
> >> > +        ret = 2;
> >> > +        break;
> >> > +    case 8:
> >> > +        ret = 4;
> >> > +        break;
> >> > +    case 16:
> >> > +        ret = 5;
> >> > +        break;
> >> > +    case 32:
> >> > +        ret = 6;
> >> > +        break;
> >> > +    default:
> >> > +        break;
> >> > +    }
> >> > +
> >> > +    return ret;
> >> > +}
> >> > +
> >> > +static void msf2_sysreg_reset(DeviceState *d)
> >> > +{
> >> > +    MSF2SysregState *s = MSF2_SYSREG(d);
> >> > +
> >> > +    DB_PRINT("RESET");
> >> > +
> >> > +    s->regs[MSSDDR_PLL_STATUS_LOW_CR] = 0x021A2358;
> >> > +    s->regs[MSSDDR_PLL_STATUS] = 0x3;
> >> > +    s->regs[MSSDDR_FACC1_CR] = msf2_divbits(s->apb0div) << 5 |
> >> > +                               msf2_divbits(s->apb1div) << 2;
> >> > +}
> >> > +
> >> > +static uint64_t msf2_sysreg_read(void *opaque, hwaddr offset,
> >> > +    unsigned size)
> >> > +{
> >> > +    MSF2SysregState *s = opaque;
> >> > +    offset /= 4;
> >>
> >> Probably best to use a bitshift.
> >
> >
> > Ok will change.
> >>
> >>
> >> > +    uint32_t ret = 0;
> >> > +
> >> > +    if (offset < ARRAY_SIZE(s->regs)) {
> >> > +        ret = s->regs[offset];
> >> > +        DB_PRINT("addr: 0x%08" HWADDR_PRIx " data: 0x%08" PRIx32,
> >> > +                    offset * 4, ret);
> >>
> >> Bitshift here as well.
> >
> >
> > Ok will change.
> >>
> >>
> >> > +    } else {
> >> > +        qemu_log_mask(LOG_GUEST_ERROR,
> >> > +                    "%s: Bad offset 0x%08" HWADDR_PRIx "\n",
> __func__,
> >> > +                    offset * 4);
> >> > +    }
> >> > +
> >> > +    return ret;
> >> > +}
> >> > +
> >> > +static void msf2_sysreg_write(void *opaque, hwaddr offset,
> >> > +                          uint64_t val, unsigned size)
> >> > +{
> >> > +    MSF2SysregState *s = (MSF2SysregState *)opaque;
> >> > +    uint32_t newval = val;
> >> > +    uint32_t oldval;
> >> > +
> >> > +    DB_PRINT("addr: 0x%08" HWADDR_PRIx " data: 0x%08" PRIx64,
> >> > +            offset, val);
> >> > +
> >> > +    offset /= 4;
> >>
> >> Same here
> >
> >
> > Ok will change
> >>
> >>
> >> > +
> >> > +    switch (offset) {
> >> > +    case MSSDDR_PLL_STATUS:
> >> > +        break;
> >> > +
> >> > +    case ESRAM_CR:
> >> > +        oldval = s->regs[ESRAM_CR];
> >> > +        if (oldval ^ newval) {
> >> > +            qemu_log_mask(LOG_GUEST_ERROR,
> >> > +                       TYPE_MSF2_SYSREG": eSRAM remapping not
> >> > supported\n");
> >> > +            abort();
> >>
> >> The guest should not be able to kill QEMU, a guest error should never
> >> result in an abort.
> >
> >
> > Philippe suggested to abort because:
> > If guest tries to remap since firmware do a remap, the code flow will be
> > completely wrong.
> > Reporting a GUEST_ERROR here is not enough since code flow continuing
> would
> > be
> > pretty hard to understand/debug.
>
> I don't see how it will be that hard to debug as QEMU will tell you
> that the guest is doing something wrong.
>
> You can't allow the guest to abort or exit QEMU. It's a security
> liability issue and specifically mentioned as not allowed:
> https://github.com/qemu/qemu/blob/master/HACKING#L230
>
> Ok. Lets hear from Philippe. Philippe?

Thanks,
Sundeep


> Thanks,
> Alistair
>
> > We decided to abort for now.
>