Re: [Qemu-devel] [PATCH v2 1/1] xen-hvm.c: Add support for Xen access to vmport

[Don Slutz <dslutz@verizon.com>]

On 10/03/14 05:52, Stefano Stabellini wrote:
> On Thu, 2 Oct 2014, Don Slutz wrote:
>> This adds synchronisation of the 6 vcpu registers (only 32bits of
>> them) that vmport.c needs between Xen and QEMU.
>>
>> This is to avoid a 2nd and 3rd exchange between QEMU and Xen to
>> fetch and put these 6 vcpu registers used by the code in vmport.c
>> and vmmouse.c
>>
>> Add new array to XenIOState that allows selection of current_cpu by
>> ioreq_id.
>>
>> Now pass XenIOState to handle_ioreq().
>>
>> Add new routines regs_to_cpu(), regs_from_cpu(), and
>> handle_vmport_ioreq().
>>
>> Signed-off-by: Don Slutz <dslutz@verizon.com>
>> ---
>> v2:
>>     More info in commit message.
>>         Added vmware_ioreq_t
>>        Added cpu_by_ioreq_id.
>>        Set current_cpu in regs_to_cpu(), clear in regs_from_cpu().
>>        Drop all changes to vmport.c
>>
>>   xen-hvm.c | 152 +++++++++++++++++++++++++++++++++++++++++++++++++++++++-------
>>   1 file changed, 137 insertions(+), 15 deletions(-)
>>
>> diff --git a/xen-hvm.c b/xen-hvm.c
>> index 05e522c..d80f21c 100644
>> --- a/xen-hvm.c
>> +++ b/xen-hvm.c
>> @@ -41,6 +41,31 @@ static MemoryRegion *framebuffer;
>>   static bool xen_in_migration;
>>   
>>   /* Compatibility with older version */
>> +
>> +/* This allows QEMU to build on a system that has Xen 4.5 or earlier
>> + * installed.  This here (not in hw/xen/xen_common.h) because xen/hvm/ioreq.h
>> + * needs to be included before this block and hw/xen/xen_common.h needs to
>> + * be included before xen/hvm/ioreq.h
>> + */
>> +#ifndef IOREQ_TYPE_VMWARE_PORT
>> +#define IOREQ_TYPE_VMWARE_PORT  3
>> +struct vmware_ioreq {
>> +        uint32_t esi;
>> +        uint32_t edi;
>> +        uint32_t eax;
>> +        uint32_t ebx;
>> +        uint32_t ecx;
>> +        uint32_t edx;
>> +        uint32_t vp_eport; /* evtchn for notifications to/from device model */
>> +        uint16_t addr;
>> +        uint8_t  state:4;
>> +        uint8_t  dir:1;    /* 1=read, 0=write */
>> +        uint8_t  size:3;
>> +        uint8_t  type;     /* I/O type */
>> +};
>> +typedef struct vmware_ioreq vmware_ioreq_t;
>> +#endif
> Why here instead of include/hw/xen/xen_common.h?
>

See code comment above.  Copied here just to make sure.


+
+/* This allows QEMU to build on a system that has Xen 4.5 or earlier
+ * installed.  This here (not in hw/xen/xen_common.h) because xen/hvm/ioreq.h
+ * needs to be included before this block and hw/xen/xen_common.h needs to
+ * be included before xen/hvm/ioreq.h
+ */



>>   #if __XEN_LATEST_INTERFACE_VERSION__ < 0x0003020a
>>   static inline uint32_t xen_vcpu_eport(shared_iopage_t *shared_page, int i)
>>   {
>> @@ -81,6 +106,7 @@ typedef struct XenIOState {
>>       shared_iopage_t *shared_page;
>>       buffered_iopage_t *buffered_io_page;
>>       QEMUTimer *buffered_io_timer;
>> +    CPUState **cpu_by_ioreq_id;
>>       /* the evtchn port for polling the notification, */
>>       evtchn_port_t *ioreq_local_port;
>>       /* evtchn local port for buffered io */
>> @@ -101,6 +127,8 @@ typedef struct XenIOState {
>>       Notifier wakeup;
>>   } XenIOState;
>>   
>> +static void handle_ioreq(XenIOState *state, ioreq_t *req);
>> +
>>   /* Xen specific function for piix pci */
>>   
>>   int xen_pci_slot_get_pirq(PCIDevice *pci_dev, int irq_num)
>> @@ -596,11 +624,23 @@ static ioreq_t *cpu_get_ioreq_from_shared_memory(XenIOState *state, int vcpu)
>>       ioreq_t *req = xen_vcpu_ioreq(state->shared_page, vcpu);
>>   
>>       if (req->state != STATE_IOREQ_READY) {
>> -        DPRINTF("I/O request not ready: "
>> -                "%x, ptr: %x, port: %"PRIx64", "
>> -                "data: %"PRIx64", count: %" FMT_ioreq_size ", size: %" FMT_ioreq_size "\n",
>> -                req->state, req->data_is_ptr, req->addr,
>> -                req->data, req->count, req->size);
>> +        if (req->type != IOREQ_TYPE_VMWARE_PORT) {
>> +            DPRINTF("I/O request not ready: "
>> +                    "%x, ptr: %x, port: %"PRIx64", "
>> +                    "data: %"PRIx64", count: %" FMT_ioreq_size ", size: %"
>> +                    FMT_ioreq_size "\n",
>> +                    req->state, req->data_is_ptr, req->addr,
>> +                    req->data, req->count, req->size);
>> +        } else {
>> +#ifdef DEBUG_XEN_HVM
>> +            vmware_ioreq_t *vp = (vmware_ioreq_t *)req;
>> +            DPRINTF("I/O VMware request not ready: "
>> +                    "%x, ptr: 0, port: %x, data: %x"
>> +                    ", count: 1, size: %d\n",
>> +                    vp->state, (uint16_t)vp->edx, vp->eax,
>> +                    vp->size);
>> +#endif
>> +        }
>>           return NULL;
>>       }
>>   
>> @@ -773,10 +813,73 @@ static void cpu_ioreq_move(ioreq_t *req)
>>       }
>>   }
>>   
>> -static void handle_ioreq(ioreq_t *req)
>> +static void regs_to_cpu(XenIOState *state, vmware_ioreq_t *vmport_req)
>> +{
>> +    X86CPU *cpu;
>> +    CPUX86State *env;
>> +
>> +    if (!state->cpu_by_ioreq_id[0]) {
>> +        CPUState *cpu_state;
>> +
>> +        CPU_FOREACH(cpu_state) {
>> +            state->cpu_by_ioreq_id[cpu_state->cpu_index] = cpu_state;
>> +        }
>> +    }
> This is just the initialization, isn't it?
> It would be best to move it to an initialization function then.
>

A new initialization function would need to be added.  A new call to it 
would need
to be added (not sure where the best place is).  Since the overhead here is
small I went with the less intrusive change.

>> +    current_cpu = state->cpu_by_ioreq_id[state->send_vcpu];
>> +    cpu = X86_CPU(current_cpu);
>> +    env = &cpu->env;
>> +    env->regs[R_EAX] = vmport_req->eax;
>> +    env->regs[R_EBX] = vmport_req->ebx;
>> +    env->regs[R_ECX] = vmport_req->ecx;
>> +    env->regs[R_EDX] = vmport_req->edx;
>> +    env->regs[R_ESI] = vmport_req->esi;
>> +    env->regs[R_EDI] = vmport_req->edi;
>> +}
>> +
>> +static void regs_from_cpu(XenIOState *state, vmware_ioreq_t *vmport_req,
>> +                          ioreq_t *req)
>> +{
>> +    X86CPU *cpu = X86_CPU(current_cpu);
>> +    CPUX86State *env = &cpu->env;
>> +
>> +    assert(sizeof(*vmport_req) == sizeof(*req));
>> +    assert(offsetof(ioreq_t, type) == offsetof(vmware_ioreq_t, type));
>> +    assert(offsetof(ioreq_t, vp_eport) == offsetof(vmware_ioreq_t, vp_eport));
>> +
>> +    vmport_req->eax = env->regs[R_EAX];
>> +    vmport_req->ebx = env->regs[R_EBX];
>> +    vmport_req->ecx = env->regs[R_ECX];
>> +    vmport_req->edx = env->regs[R_EDX];
>> +    vmport_req->esi = env->regs[R_ESI];
>> +    vmport_req->edi = env->regs[R_EDI];
>> +    current_cpu = NULL;
>> +}
>> +
>> +static void handle_vmport_ioreq(XenIOState *state, vmware_ioreq_t *vmport_req)
>> +{
>> +    ioreq_t req;
>> +
>> +    memset(&req, 0x00, sizeof(req));
>> +
>> +    req.size = vmport_req->size;
>> +    req.count = 1;
>> +    req.addr = vmport_req->addr;
>> +    req.data = vmport_req->eax;
>> +    req.state = STATE_IOREQ_READY;
>> +    req.dir = vmport_req->dir;
>> +    req.df = 0;
>> +    req.type = IOREQ_TYPE_PIO;
>> +    req.data_is_ptr = 0;
>> +
>> +    regs_to_cpu(state, vmport_req);
>> +    handle_ioreq(state, &req);
>> +    regs_from_cpu(state, vmport_req, &req);
>> +}
> I think that this is far better than the previous version
>      
>    

Good.

    -Don Slutz