Re: [Qemu-ppc] [RFC PATCH 14/26] ppc/xive: add MMIO handlers to the XIVE interrupt presenter model

[Cédric Le Goater]

On 07/24/2017 08:35 AM, David Gibson wrote:
> On Wed, Jul 05, 2017 at 07:13:27PM +0200, Cédric Le Goater wrote:
>> The Thread Interrupt Management Area for the OS is mostly used to
>> acknowledge interrupts and set the CPPR of the CPU.
>>
>> The TIMA is mapped at the same address for each CPU. 'current_cpu' is
>> used to retrieve the targeted interrupt presenter object.
>>
>> Signed-off-by: Cédric Le Goater <address@hidden>
> 
> Am I right in thinking that this shoehorns the XIVE TIMA state into
> the existing XICS ICP object.  That.. doesn't seem like a good idea.

The TIMA memory region is under the XIVE object because it is 
unique for the system. The lookup of the ICP is simply done using 
'current_cpu'. The TIMA state is under the ICPState, yes, but this 
model does not seem incorrect to me as this state contains the 
interrupt information presented to a CPU.   

Thanks,

C.

>> ---
>>  hw/intc/xive-internal.h |   4 ++
>>  hw/intc/xive.c          | 187 
>> ++++++++++++++++++++++++++++++++++++++++++++++++
>>  2 files changed, 191 insertions(+)
>>
>> diff --git a/hw/intc/xive-internal.h b/hw/intc/xive-internal.h
>> index ba5e648a5258..5e8b78a1ea6a 100644
>> --- a/hw/intc/xive-internal.h
>> +++ b/hw/intc/xive-internal.h
>> @@ -200,6 +200,10 @@ struct XIVE {
>>      /* ESB and TIMA memory location */
>>      hwaddr       vc_base;
>>      MemoryRegion esb_iomem;
>> +
>> +    uint32_t     tm_shift;
>> +    hwaddr       tm_base;
>> +    MemoryRegion tm_iomem;
>>  };
>>  
>>  void xive_reset(void *dev);
>> diff --git a/hw/intc/xive.c b/hw/intc/xive.c
>> index c08a4f8efb58..82b2f0dcda0b 100644
>> --- a/hw/intc/xive.c
>> +++ b/hw/intc/xive.c
>> @@ -26,6 +26,180 @@
>>  
>>  #include "xive-internal.h"
>>  
>> +static uint8_t priority_to_ipb(uint8_t priority)
>> +{
>> +    return priority < XIVE_EQ_PRIORITY_COUNT ? 1 << (7 - priority) : 0;
>> +}
>> +
>> +static uint64_t xive_icp_accept(XiveICPState *xicp)
>> +{
>> +    ICPState *icp = ICP(xicp);
>> +    uint8_t nsr = xicp->tima_os[TM_NSR];
>> +
>> +    qemu_irq_lower(icp->output);
>> +
>> +    if (xicp->tima_os[TM_NSR] & TM_QW1_NSR_EO) {
>> +        uint8_t cppr = xicp->tima_os[TM_PIPR];
>> +
>> +        xicp->tima_os[TM_CPPR] = cppr;
>> +
>> +        /* Reset the pending buffer bit */
>> +        xicp->tima_os[TM_IPB] &= ~priority_to_ipb(cppr);
>> +
>> +        /* Drop Exception bit for OS */
>> +        xicp->tima_os[TM_NSR] &= ~TM_QW1_NSR_EO;
>> +    }
>> +
>> +    return (nsr << 8) | xicp->tima_os[TM_CPPR];
>> +}
>> +
>> +static void xive_icp_set_cppr(XiveICPState *xicp, uint8_t cppr)
>> +{
>> +    if (cppr > XIVE_PRIORITY_MAX) {
>> +        cppr = 0xff;
>> +    }
>> +
>> +    xicp->tima_os[TM_CPPR] = cppr;
>> +}
>> +
>> +/*
>> + * Thread Interrupt Management Area MMIO
>> + */
>> +static uint64_t xive_tm_read_special(XiveICPState *icp, hwaddr offset,
>> +                                     unsigned size)
>> +{
>> +    uint64_t ret = -1;
>> +
>> +    if (offset == TM_SPC_ACK_OS_REG && size == 2) {
>> +        ret = xive_icp_accept(icp);
>> +    } else {
>> +        qemu_log_mask(LOG_GUEST_ERROR, "XIVE: invalid TIMA read @%"
>> +                      HWADDR_PRIx" size %d\n", offset, size);
>> +    }
>> +
>> +    return ret;
>> +}
>> +
>> +static uint64_t xive_tm_read(void *opaque, hwaddr offset, unsigned size)
>> +{
>> +    PowerPCCPU *cpu = POWERPC_CPU(current_cpu);
>> +    XiveICPState *icp = XIVE_ICP(cpu->intc);
>> +    uint64_t ret = -1;
>> +    int i;
>> +
>> +    if (offset >= TM_SPC_ACK_EBB) {
>> +        return xive_tm_read_special(icp, offset, size);
>> +    }
>> +
>> +    if (offset & TM_QW1_OS) {
>> +        switch (size) {
>> +        case 1:
>> +        case 2:
>> +        case 4:
>> +        case 8:
>> +            if (QEMU_IS_ALIGNED(offset, size)) {
>> +                ret = 0;
>> +                for (i = 0; i < size; i++) {
>> +                    ret |= icp->tima[offset + i] << (8 * i);
>> +                }
>> +            } else {
>> +                qemu_log_mask(LOG_GUEST_ERROR,
>> +                              "XIVE: invalid TIMA read alignment @%"
>> +                              HWADDR_PRIx" size %d\n", offset, size);
>> +            }
>> +            break;
>> +        default:
>> +            g_assert_not_reached();
>> +        }
>> +    } else {
>> +        qemu_log_mask(LOG_UNIMP, "XIVE: does handle non-OS TIMA ring @%"
>> +                      HWADDR_PRIx"\n", offset);
>> +    }
>> +
>> +    return ret;
>> +}
>> +
>> +static bool xive_tm_is_readonly(uint8_t index)
>> +{
>> +    /* Let's be optimistic and prepare ground for HV mode support */
>> +    switch (index) {
>> +    case TM_QW1_OS + TM_CPPR:
>> +        return false;
>> +    default:
>> +        return true;
>> +    }
>> +}
>> +
>> +static void xive_tm_write_special(XiveICPState *xicp, hwaddr offset,
>> +                                  uint64_t value, unsigned size)
>> +{
>> +    if (offset == TM_SPC_SET_OS_PENDING && size == 1) {
>> +        xicp->tima_os[TM_IPB] |= priority_to_ipb(value & 0xff);
>> +    } else {
>> +        qemu_log_mask(LOG_GUEST_ERROR, "XIVE: invalid TIMA write @%"
>> +                      HWADDR_PRIx" size %d\n", offset, size);
>> +    }
>> +
>> +    /* TODO: support TM_SPC_ACK_OS_EL */
>> +}
>> +
>> +static void xive_tm_write(void *opaque, hwaddr offset,
>> +                           uint64_t value, unsigned size)
>> +{
>> +    PowerPCCPU *cpu = POWERPC_CPU(current_cpu);
>> +    XiveICPState *icp = XIVE_ICP(cpu->intc);
>> +    int i;
>> +
>> +    if (offset >= TM_SPC_ACK_EBB) {
>> +        xive_tm_write_special(icp, offset, value, size);
>> +        return;
>> +    }
>> +
>> +    if (offset & TM_QW1_OS) {
>> +        switch (size) {
>> +        case 1:
>> +            if (offset == TM_QW1_OS + TM_CPPR) {
>> +                xive_icp_set_cppr(icp, value & 0xff);
>> +            }
>> +            break;
>> +        case 4:
>> +        case 8:
>> +            if (QEMU_IS_ALIGNED(offset, size)) {
>> +                for (i = 0; i < size; i++) {
>> +                    if (!xive_tm_is_readonly(offset + i)) {
>> +                        icp->tima[offset + i] = (value >> (8 * i)) & 0xff;
>> +                    }
>> +                }
>> +            } else {
>> +                qemu_log_mask(LOG_GUEST_ERROR, "XIVE: invalid TIMA write @%"
>> +                              HWADDR_PRIx" size %d\n", offset, size);
>> +            }
>> +            break;
>> +        default:
>> +            qemu_log_mask(LOG_GUEST_ERROR, "XIVE: invalid TIMA write @%"
>> +                          HWADDR_PRIx" size %d\n", offset, size);
>> +        }
>> +    } else {
>> +        qemu_log_mask(LOG_UNIMP, "XIVE: does handle non-OS TIMA ring @%"
>> +                      HWADDR_PRIx"\n", offset);
>> +    }
>> +}
>> +
>> +
>> +static const MemoryRegionOps xive_tm_ops = {
>> +    .read = xive_tm_read,
>> +    .write = xive_tm_write,
>> +    .endianness = DEVICE_BIG_ENDIAN,
>> +    .valid = {
>> +        .min_access_size = 1,
>> +        .max_access_size = 8,
>> +    },
>> +    .impl = {
>> +        .min_access_size = 1,
>> +        .max_access_size = 8,
>> +    },
>> +};
>> +
>>  static void xive_icp_reset(ICPState *icp)
>>  {
>>      XiveICPState *xicp = XIVE_ICP(icp);
>> @@ -453,6 +627,11 @@ static const TypeInfo xive_ics_info = {
>>  #define P9_MMIO_BASE     0x006000000000000ull
>>  #define P9_CHIP_BASE(id) (P9_MMIO_BASE | (0x40000000000ull * (uint64_t) 
>> (id)))
>>  
>> +/* Thread Interrupt Management Area MMIO */
>> +#define TM_BAR_DEFAULT   0x30203180000ull
>> +#define TM_SHIFT         16
>> +#define TM_BAR_SIZE      (XIVE_TM_RING_COUNT * (1 << TM_SHIFT))
>> +
>>  static uint64_t xive_esb_default_read(void *p, hwaddr offset, unsigned size)
>>  {
>>      qemu_log_mask(LOG_UNIMP, "%s: 0x%" HWADDR_PRIx " [%u]\n",
>> @@ -541,6 +720,14 @@ static void xive_realize(DeviceState *dev, Error **errp)
>>                            NULL, "xive.esb", VC_BAR_SIZE);
>>      sysbus_init_mmio(SYS_BUS_DEVICE(dev), &x->esb_iomem);
>>  
>> +    /* TM BAR. Same address for each chip */
>> +    x->tm_base = (P9_MMIO_BASE | TM_BAR_DEFAULT);
>> +    x->tm_shift = TM_SHIFT;
>> +
>> +    memory_region_init_io(&x->tm_iomem, OBJECT(x), &xive_tm_ops, x,
>> +                          "xive.tm", TM_BAR_SIZE);
>> +    sysbus_init_mmio(SYS_BUS_DEVICE(dev), &x->tm_iomem);
>> +
>>      qemu_register_reset(xive_reset, dev);
>>  }
>>  
>