Re: [Qemu-devel] [PATCH 13/25] spapr: introduce the XIVE Event Queues

[Cédric Le Goater]

On 11/23/2017 09:31 PM, Benjamin Herrenschmidt wrote:
> On Thu, 2017-11-23 at 14:29 +0100, Cédric Le Goater wrote:
>> The Event Queue Descriptor (EQD) table, also known as Event Notification
>> Descriptor (END), is one of the internal tables the XIVE interrupt
>> controller uses to redirect exception from event sources to CPU
>> threads.
> 
> Keep in mind tha we want to only expose to the guest priorities 0..6
> as priority 7 will not be available with KVM on DD2.0 chips.

The hcall patch 19 introduces the "ibm,plat-res-int-priorities" property.
The priority ranges reserved by the hypervisor are the following :

    static const uint32_t reserved_priorities[] = {
        7,    /* start */
        0xf8, /* count */
    };

So The Linux driver is expected to choose priority 6. The priority
validity is then checked in each hcall returning H_P4/H_P3 in case of 
failure.  

But it is true that we scale the arrays with :
 
    #define XIVE_PRIORITY_MAX  7

Do you want QEMU to completely remove prio 7 ? 

C. 

>> The EQD specifies on which Event Queue the event data should be posted
>> when an exception occurs (later on pulled by the OS) and which server
>> (VPD in XIVE terminology) to notify. The Event Queue is a much more
>> complex structure but we start with a simple model for the sPAPR
>> machine.
>>
>> There is one XiveEQ per priority and the model chooses to store them
>> under the Xive Interrupt presenter model. It will be retrieved, just
>> like for XICS, through the 'intc' object pointer of the CPU.
>>
>> The EQ indexing follows a simple pattern:
>>
>>        (server << 3) | (priority & 0x7)
>>
>> Signed-off-by: Cédric Le Goater <address@hidden>
>> ---
>>  hw/intc/spapr_xive.c    | 56 
>> +++++++++++++++++++++++++++++++++++++++++++++++++
>>  hw/intc/xive-internal.h | 50 +++++++++++++++++++++++++++++++++++++++++++
>>  2 files changed, 106 insertions(+)
>>
>> diff --git a/hw/intc/spapr_xive.c b/hw/intc/spapr_xive.c
>> index 554b25e0884c..983317a6b3f6 100644
>> --- a/hw/intc/spapr_xive.c
>> +++ b/hw/intc/spapr_xive.c
>> @@ -23,6 +23,7 @@
>>  #include "sysemu/dma.h"
>>  #include "monitor/monitor.h"
>>  #include "hw/ppc/spapr_xive.h"
>> +#include "hw/ppc/spapr.h"
>>  #include "hw/ppc/xics.h"
>>  
>>  #include "xive-internal.h"
>> @@ -34,6 +35,8 @@ struct sPAPRXiveICP {
>>      uint8_t   tima[TM_RING_COUNT * 0x10];
>>      uint8_t   *tima_os;
>>      qemu_irq  output;
>> +
>> +    XiveEQ    eqt[XIVE_PRIORITY_MAX + 1];
>>  };
>>  
>>  static uint64_t spapr_xive_icp_accept(sPAPRXiveICP *icp)
>> @@ -183,6 +186,13 @@ static const MemoryRegionOps spapr_xive_tm_ops = {
>>      },
>>  };
>>  
>> +static sPAPRXiveICP *spapr_xive_icp_get(sPAPRXive *xive, int server)
>> +{
>> +    PowerPCCPU *cpu = spapr_find_cpu(server);
>> +
>> +    return cpu ? SPAPR_XIVE_ICP(cpu->intc) : NULL;
>> +}
>> +
>>  static void spapr_xive_irq(sPAPRXive *xive, int lisn)
>>  {
>>  
>> @@ -632,6 +642,8 @@ static void spapr_xive_icp_reset(void *dev)
>>      sPAPRXiveICP *xicp = SPAPR_XIVE_ICP(dev);
>>  
>>      memset(xicp->tima, 0, sizeof(xicp->tima));
>> +
>> +    memset(xicp->eqt, 0, sizeof(xicp->eqt));
>>  }
>>  
>>  static void spapr_xive_icp_realize(DeviceState *dev, Error **errp)
>> @@ -683,6 +695,23 @@ static void spapr_xive_icp_init(Object *obj)
>>      xicp->tima_os = &xicp->tima[TM_QW1_OS];
>>  }
>>  
>> +static const VMStateDescription vmstate_spapr_xive_icp_eq = {
>> +    .name = TYPE_SPAPR_XIVE_ICP "/eq",
>> +    .version_id = 1,
>> +    .minimum_version_id = 1,
>> +    .fields = (VMStateField []) {
>> +        VMSTATE_UINT32(w0, XiveEQ),
>> +        VMSTATE_UINT32(w1, XiveEQ),
>> +        VMSTATE_UINT32(w2, XiveEQ),
>> +        VMSTATE_UINT32(w3, XiveEQ),
>> +        VMSTATE_UINT32(w4, XiveEQ),
>> +        VMSTATE_UINT32(w5, XiveEQ),
>> +        VMSTATE_UINT32(w6, XiveEQ),
>> +        VMSTATE_UINT32(w7, XiveEQ),
>> +        VMSTATE_END_OF_LIST()
>> +    },
>> +};
>> +
>>  static bool vmstate_spapr_xive_icp_needed(void *opaque)
>>  {
>>      /* TODO check machine XIVE support */
>> @@ -696,6 +725,8 @@ static const VMStateDescription vmstate_spapr_xive_icp = 
>> {
>>      .needed = vmstate_spapr_xive_icp_needed,
>>      .fields = (VMStateField[]) {
>>          VMSTATE_BUFFER(tima, sPAPRXiveICP),
>> +        VMSTATE_STRUCT_ARRAY(eqt, sPAPRXiveICP, (XIVE_PRIORITY_MAX + 1), 1,
>> +                             vmstate_spapr_xive_icp_eq, XiveEQ),
>>          VMSTATE_END_OF_LIST()
>>      },
>>  };
>> @@ -755,3 +786,28 @@ bool spapr_xive_irq_unset(sPAPRXive *xive, uint32_t 
>> lisn)
>>      ive->w &= ~IVE_VALID;
>>      return true;
>>  }
>> +
>> +/*
>> + * Use a simple indexing for the EQs.
>> + */
>> +XiveEQ *spapr_xive_get_eq(sPAPRXive *xive, uint32_t eq_idx)
>> +{
>> +    int priority = eq_idx & 0x7;
>> +    sPAPRXiveICP *xicp = spapr_xive_icp_get(xive, eq_idx >> 3);
>> +
>> +    return xicp ? &xicp->eqt[priority] : NULL;
>> +}
>> +
>> +bool spapr_xive_eq_for_server(sPAPRXive *xive, uint32_t server,
>> +                              uint8_t priority, uint32_t *out_eq_idx)
>> +{
>> +    if (priority > XIVE_PRIORITY_MAX) {
>> +        return false;
>> +    }
>> +
>> +    if (out_eq_idx) {
>> +        *out_eq_idx = (server << 3) | (priority & 0x7);
>> +    }
>> +
>> +    return true;
>> +}
>> diff --git a/hw/intc/xive-internal.h b/hw/intc/xive-internal.h
>> index 7d329f203a9b..c3949671aa03 100644
>> --- a/hw/intc/xive-internal.h
>> +++ b/hw/intc/xive-internal.h
>> @@ -131,9 +131,59 @@ typedef struct XiveIVE {
>>  #define IVE_EQ_DATA     PPC_BITMASK(33, 63)      /* Data written to the EQ 
>> */
>>  } XiveIVE;
>>  
>> +/* EQ */
>> +typedef struct XiveEQ {
>> +        uint32_t        w0;
>> +#define EQ_W0_VALID             PPC_BIT32(0)
>> +#define EQ_W0_ENQUEUE           PPC_BIT32(1)
>> +#define EQ_W0_UCOND_NOTIFY      PPC_BIT32(2)
>> +#define EQ_W0_BACKLOG           PPC_BIT32(3)
>> +#define EQ_W0_PRECL_ESC_CTL     PPC_BIT32(4)
>> +#define EQ_W0_ESCALATE_CTL      PPC_BIT32(5)
>> +#define EQ_W0_END_OF_INTR       PPC_BIT32(6)
>> +#define EQ_W0_QSIZE             PPC_BITMASK32(12, 15)
>> +#define EQ_W0_SW0               PPC_BIT32(16)
>> +#define EQ_W0_FIRMWARE          EQ_W0_SW0 /* Owned by FW */
>> +#define EQ_QSIZE_4K             0
>> +#define EQ_QSIZE_64K            4
>> +#define EQ_W0_HWDEP             PPC_BITMASK32(24, 31)
>> +        uint32_t        w1;
>> +#define EQ_W1_ESn               PPC_BITMASK32(0, 1)
>> +#define EQ_W1_ESn_P             PPC_BIT32(0)
>> +#define EQ_W1_ESn_Q             PPC_BIT32(1)
>> +#define EQ_W1_ESe               PPC_BITMASK32(2, 3)
>> +#define EQ_W1_ESe_P             PPC_BIT32(2)
>> +#define EQ_W1_ESe_Q             PPC_BIT32(3)
>> +#define EQ_W1_GENERATION        PPC_BIT32(9)
>> +#define EQ_W1_PAGE_OFF          PPC_BITMASK32(10, 31)
>> +        uint32_t        w2;
>> +#define EQ_W2_MIGRATION_REG     PPC_BITMASK32(0, 3)
>> +#define EQ_W2_OP_DESC_HI        PPC_BITMASK32(4, 31)
>> +        uint32_t        w3;
>> +#define EQ_W3_OP_DESC_LO        PPC_BITMASK32(0, 31)
>> +        uint32_t        w4;
>> +#define EQ_W4_ESC_EQ_BLOCK      PPC_BITMASK32(4, 7)
>> +#define EQ_W4_ESC_EQ_INDEX      PPC_BITMASK32(8, 31)
>> +        uint32_t        w5;
>> +#define EQ_W5_ESC_EQ_DATA       PPC_BITMASK32(1, 31)
>> +        uint32_t        w6;
>> +#define EQ_W6_FORMAT_BIT        PPC_BIT32(8)
>> +#define EQ_W6_NVT_BLOCK         PPC_BITMASK32(9, 12)
>> +#define EQ_W6_NVT_INDEX         PPC_BITMASK32(13, 31)
>> +        uint32_t        w7;
>> +#define EQ_W7_F0_IGNORE         PPC_BIT32(0)
>> +#define EQ_W7_F0_BLK_GROUPING   PPC_BIT32(1)
>> +#define EQ_W7_F0_PRIORITY       PPC_BITMASK32(8, 15)
>> +#define EQ_W7_F1_WAKEZ          PPC_BIT32(0)
>> +#define EQ_W7_F1_LOG_SERVER_ID  PPC_BITMASK32(1, 31)
>> +} XiveEQ;
>> +
>>  #define XIVE_PRIORITY_MAX  7
>>  
>>  void spapr_xive_reset(void *dev);
>>  XiveIVE *spapr_xive_get_ive(sPAPRXive *xive, uint32_t lisn);
>> +XiveEQ *spapr_xive_get_eq(sPAPRXive *xive, uint32_t idx);
>> +bool spapr_xive_eq_for_server(sPAPRXive *xive, uint32_t server, uint8_t 
>> prio,
>> +                              uint32_t *out_eq_idx);
>>  
>>  #endif /* _INTC_XIVE_INTERNAL_H */