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Re: [Qemu-devel] [Qemu devel v6 PATCH 2/5] msf2: Microsemi Smartfusion2


From: sundeep subbaraya
Subject: Re: [Qemu-devel] [Qemu devel v6 PATCH 2/5] msf2: Microsemi Smartfusion2 System Register block.
Date: Fri, 21 Jul 2017 14:50:47 +0530

Hi,

Ping

On Thu, Jul 13, 2017 at 7:51 AM, sundeep subbaraya <address@hidden>
wrote:

> Hi Phiiippe,
>
> Gentle reminder.
>
> Thanks,
> Sundeep
>
>
> On Mon, Jul 10, 2017 at 1:55 PM, sundeep subbaraya <address@hidden
> > wrote:
>
>> 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.
>>>
>>
>>
>


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