diff mbox

[qemu,v13,02/16] spapr_pci: Move DMA window enablement to a helper

Message ID 1456823441-46757-3-git-send-email-aik@ozlabs.ru (mailing list archive)
State New, archived
Headers show

Commit Message

Alexey Kardashevskiy March 1, 2016, 9:10 a.m. UTC
We are going to have multiple DMA windows soon so let's start preparing.

This adds a new helper to create a DMA window and makes use of it in
sPAPRPHBState::realize().

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
---
 hw/ppc/spapr_pci.c | 40 +++++++++++++++++++++++++++-------------
 1 file changed, 27 insertions(+), 13 deletions(-)

Comments

David Gibson March 3, 2016, 1:40 a.m. UTC | #1
On Tue, Mar 01, 2016 at 08:10:27PM +1100, Alexey Kardashevskiy wrote:
> We are going to have multiple DMA windows soon so let's start preparing.
> 
> This adds a new helper to create a DMA window and makes use of it in
> sPAPRPHBState::realize().
> 
> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
> ---
>  hw/ppc/spapr_pci.c | 40 +++++++++++++++++++++++++++-------------
>  1 file changed, 27 insertions(+), 13 deletions(-)
> 
> diff --git a/hw/ppc/spapr_pci.c b/hw/ppc/spapr_pci.c
> index 3d1145e..248f20a 100644
> --- a/hw/ppc/spapr_pci.c
> +++ b/hw/ppc/spapr_pci.c
> @@ -803,6 +803,29 @@ static char *spapr_phb_get_loc_code(sPAPRPHBState *sphb, PCIDevice *pdev)
>      return buf;
>  }
>  
> +static int spapr_phb_dma_window_enable(sPAPRPHBState *sphb,
> +                                       uint32_t liobn, uint32_t page_shift,
> +                                       uint64_t window_addr,
> +                                       uint64_t window_size)
> +{
> +    sPAPRTCETable *tcet;
> +    uint32_t nb_table = window_size >> page_shift;
> +
> +    if (!nb_table) {
> +        return -1;
> +    }

The caller shouldn't do this, so this probably makes more sense as an
assert() than an error return.

> +
> +    tcet = spapr_tce_new_table(DEVICE(sphb), liobn, window_addr,
> +                               page_shift, nb_table, false);
> +    if (!tcet) {
> +        return -1;
> +    }

Since you're adding error reporting, you might as well make it via the
error API instead of a return code.  That way if we wasnt to add more
detailed error API reporting to spapr_tce_new_table() in future,
there's less to change.

> +
> +    memory_region_add_subregion(&sphb->iommu_root, tcet->bus_offset,
> +                                spapr_tce_get_iommu(tcet));
> +    return 0;
> +}
> +
>  /* Macros to operate with address in OF binding to PCI */
>  #define b_x(x, p, l)    (((x) & ((1<<(l))-1)) << (p))
>  #define b_n(x)          b_x((x), 31, 1) /* 0 if relocatable */
> @@ -1228,8 +1251,6 @@ static void spapr_phb_realize(DeviceState *dev, Error **errp)
>      int i;
>      PCIBus *bus;
>      uint64_t msi_window_size = 4096;
> -    sPAPRTCETable *tcet;
> -    uint32_t nb_table;
>  
>      if (sphb->index != (uint32_t)-1) {
>          hwaddr windows_base;
> @@ -1381,18 +1402,11 @@ static void spapr_phb_realize(DeviceState *dev, Error **errp)
>          }
>      }
>  
> -    nb_table = sphb->dma_win_size >> SPAPR_TCE_PAGE_SHIFT;
> -    tcet = spapr_tce_new_table(DEVICE(sphb), sphb->dma_liobn,
> -                               0, SPAPR_TCE_PAGE_SHIFT, nb_table, false);
> -    if (!tcet) {
> -        error_setg(errp, "Unable to create TCE table for %s",
> -                   sphb->dtbusname);
> -        return;
> -    }
> -
>      /* Register default 32bit DMA window */
> -    memory_region_add_subregion(&sphb->iommu_root, sphb->dma_win_addr,
> -                                spapr_tce_get_iommu(tcet));
> +    if (spapr_phb_dma_window_enable(sphb, sphb->dma_liobn, SPAPR_TCE_PAGE_SHIFT,
> +                                    sphb->dma_win_addr, sphb->dma_win_size)) {
> +        error_setg(errp, "Unable to create TCE table for %s", sphb->dtbusname);
> +    }
>  
>      sphb->msi = g_hash_table_new_full(g_int_hash, g_int_equal, g_free, g_free);
>  }
Alexey Kardashevskiy March 10, 2016, 5:47 a.m. UTC | #2
On 03/03/2016 12:40 PM, David Gibson wrote:
> On Tue, Mar 01, 2016 at 08:10:27PM +1100, Alexey Kardashevskiy wrote:
>> We are going to have multiple DMA windows soon so let's start preparing.
>>
>> This adds a new helper to create a DMA window and makes use of it in
>> sPAPRPHBState::realize().
>>
>> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
>> ---
>>   hw/ppc/spapr_pci.c | 40 +++++++++++++++++++++++++++-------------
>>   1 file changed, 27 insertions(+), 13 deletions(-)
>>
>> diff --git a/hw/ppc/spapr_pci.c b/hw/ppc/spapr_pci.c
>> index 3d1145e..248f20a 100644
>> --- a/hw/ppc/spapr_pci.c
>> +++ b/hw/ppc/spapr_pci.c
>> @@ -803,6 +803,29 @@ static char *spapr_phb_get_loc_code(sPAPRPHBState *sphb, PCIDevice *pdev)
>>       return buf;
>>   }
>>
>> +static int spapr_phb_dma_window_enable(sPAPRPHBState *sphb,
>> +                                       uint32_t liobn, uint32_t page_shift,
>> +                                       uint64_t window_addr,
>> +                                       uint64_t window_size)
>> +{
>> +    sPAPRTCETable *tcet;
>> +    uint32_t nb_table = window_size >> page_shift;
>> +
>> +    if (!nb_table) {
>> +        return -1;
>> +    }
>
> The caller shouldn't do this, so this probably makes more sense as an
> assert() than an error return.


@dma_win_size is a PHB property so the cli can set it to zero - where is it 
supposed to fail? When DMA won't work? This will be not really obvious for 
the user. Check dma_win_size==0 where we check mem_win_addr/...?

>
>> +
>> +    tcet = spapr_tce_new_table(DEVICE(sphb), liobn, window_addr,
>> +                               page_shift, nb_table, false);
>> +    if (!tcet) {
>> +        return -1;
>> +    }
>
> Since you're adding error reporting, you might as well make it via the
> error API instead of a return code.  That way if we wasnt to add more
> detailed error API reporting to spapr_tce_new_table() in future,
> there's less to change.

Well, the table allocation is the only real thing which may fail there and 
spapr_phb_realize() does not pass Error to the callers so 
spapr_phb_dma_window_enable() would be the first one to propagate an error 
and it just seems a bit over engineered. Should I still do that?


>> +
>> +    memory_region_add_subregion(&sphb->iommu_root, tcet->bus_offset,
>> +                                spapr_tce_get_iommu(tcet));
>> +    return 0;
>> +}
>> +
>>   /* Macros to operate with address in OF binding to PCI */
>>   #define b_x(x, p, l)    (((x) & ((1<<(l))-1)) << (p))
>>   #define b_n(x)          b_x((x), 31, 1) /* 0 if relocatable */
>> @@ -1228,8 +1251,6 @@ static void spapr_phb_realize(DeviceState *dev, Error **errp)
>>       int i;
>>       PCIBus *bus;
>>       uint64_t msi_window_size = 4096;
>> -    sPAPRTCETable *tcet;
>> -    uint32_t nb_table;
>>
>>       if (sphb->index != (uint32_t)-1) {
>>           hwaddr windows_base;
>> @@ -1381,18 +1402,11 @@ static void spapr_phb_realize(DeviceState *dev, Error **errp)
>>           }
>>       }
>>
>> -    nb_table = sphb->dma_win_size >> SPAPR_TCE_PAGE_SHIFT;
>> -    tcet = spapr_tce_new_table(DEVICE(sphb), sphb->dma_liobn,
>> -                               0, SPAPR_TCE_PAGE_SHIFT, nb_table, false);
>> -    if (!tcet) {
>> -        error_setg(errp, "Unable to create TCE table for %s",
>> -                   sphb->dtbusname);
>> -        return;
>> -    }
>> -
>>       /* Register default 32bit DMA window */
>> -    memory_region_add_subregion(&sphb->iommu_root, sphb->dma_win_addr,
>> -                                spapr_tce_get_iommu(tcet));
>> +    if (spapr_phb_dma_window_enable(sphb, sphb->dma_liobn, SPAPR_TCE_PAGE_SHIFT,
>> +                                    sphb->dma_win_addr, sphb->dma_win_size)) {
>> +        error_setg(errp, "Unable to create TCE table for %s", sphb->dtbusname);
>> +    }
>>
>>       sphb->msi = g_hash_table_new_full(g_int_hash, g_int_equal, g_free, g_free);
>>   }
>
David Gibson March 15, 2016, 5:30 a.m. UTC | #3
On Thu, Mar 10, 2016 at 04:47:04PM +1100, Alexey Kardashevskiy wrote:
> On 03/03/2016 12:40 PM, David Gibson wrote:
> >On Tue, Mar 01, 2016 at 08:10:27PM +1100, Alexey Kardashevskiy wrote:
> >>We are going to have multiple DMA windows soon so let's start preparing.
> >>
> >>This adds a new helper to create a DMA window and makes use of it in
> >>sPAPRPHBState::realize().
> >>
> >>Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
> >>---
> >>  hw/ppc/spapr_pci.c | 40 +++++++++++++++++++++++++++-------------
> >>  1 file changed, 27 insertions(+), 13 deletions(-)
> >>
> >>diff --git a/hw/ppc/spapr_pci.c b/hw/ppc/spapr_pci.c
> >>index 3d1145e..248f20a 100644
> >>--- a/hw/ppc/spapr_pci.c
> >>+++ b/hw/ppc/spapr_pci.c
> >>@@ -803,6 +803,29 @@ static char *spapr_phb_get_loc_code(sPAPRPHBState *sphb, PCIDevice *pdev)
> >>      return buf;
> >>  }
> >>
> >>+static int spapr_phb_dma_window_enable(sPAPRPHBState *sphb,
> >>+                                       uint32_t liobn, uint32_t page_shift,
> >>+                                       uint64_t window_addr,
> >>+                                       uint64_t window_size)
> >>+{
> >>+    sPAPRTCETable *tcet;
> >>+    uint32_t nb_table = window_size >> page_shift;
> >>+
> >>+    if (!nb_table) {
> >>+        return -1;
> >>+    }
> >
> >The caller shouldn't do this, so this probably makes more sense as an
> >assert() than an error return.
> 
> 
> @dma_win_size is a PHB property so the cli can set it to zero - where is it
> supposed to fail? When DMA won't work? This will be not really obvious for
> the user. Check dma_win_size==0 where we check mem_win_addr/...?

Ah.. good point.  It could be checked in the caller, but it doesn't
make a lot of sense to.

> >>+
> >>+    tcet = spapr_tce_new_table(DEVICE(sphb), liobn, window_addr,
> >>+                               page_shift, nb_table, false);
> >>+    if (!tcet) {
> >>+        return -1;
> >>+    }
> >
> >Since you're adding error reporting, you might as well make it via the
> >error API instead of a return code.  That way if we wasnt to add more
> >detailed error API reporting to spapr_tce_new_table() in future,
> >there's less to change.
> 
> Well, the table allocation is the only real thing which may fail there and
> spapr_phb_realize() does not pass Error to the callers

?? I'm not sure what you mean by that.

> so
> spapr_phb_dma_window_enable() would be the first one to propagate an error
> and it just seems a bit over engineered. Should I still do that?

Yes.

You can argue it's overengineered, but better we move towards
overengineered in a consistent way, than continue to use a mishmash of
error codes and the error api.


> 
> 
> >>+
> >>+    memory_region_add_subregion(&sphb->iommu_root, tcet->bus_offset,
> >>+                                spapr_tce_get_iommu(tcet));
> >>+    return 0;
> >>+}
> >>+
> >>  /* Macros to operate with address in OF binding to PCI */
> >>  #define b_x(x, p, l)    (((x) & ((1<<(l))-1)) << (p))
> >>  #define b_n(x)          b_x((x), 31, 1) /* 0 if relocatable */
> >>@@ -1228,8 +1251,6 @@ static void spapr_phb_realize(DeviceState *dev, Error **errp)
> >>      int i;
> >>      PCIBus *bus;
> >>      uint64_t msi_window_size = 4096;
> >>-    sPAPRTCETable *tcet;
> >>-    uint32_t nb_table;
> >>
> >>      if (sphb->index != (uint32_t)-1) {
> >>          hwaddr windows_base;
> >>@@ -1381,18 +1402,11 @@ static void spapr_phb_realize(DeviceState *dev, Error **errp)
> >>          }
> >>      }
> >>
> >>-    nb_table = sphb->dma_win_size >> SPAPR_TCE_PAGE_SHIFT;
> >>-    tcet = spapr_tce_new_table(DEVICE(sphb), sphb->dma_liobn,
> >>-                               0, SPAPR_TCE_PAGE_SHIFT, nb_table, false);
> >>-    if (!tcet) {
> >>-        error_setg(errp, "Unable to create TCE table for %s",
> >>-                   sphb->dtbusname);
> >>-        return;
> >>-    }
> >>-
> >>      /* Register default 32bit DMA window */
> >>-    memory_region_add_subregion(&sphb->iommu_root, sphb->dma_win_addr,
> >>-                                spapr_tce_get_iommu(tcet));
> >>+    if (spapr_phb_dma_window_enable(sphb, sphb->dma_liobn, SPAPR_TCE_PAGE_SHIFT,
> >>+                                    sphb->dma_win_addr, sphb->dma_win_size)) {
> >>+        error_setg(errp, "Unable to create TCE table for %s", sphb->dtbusname);
> >>+    }
> >>
> >>      sphb->msi = g_hash_table_new_full(g_int_hash, g_int_equal, g_free, g_free);
> >>  }
> >
> 
>
diff mbox

Patch

diff --git a/hw/ppc/spapr_pci.c b/hw/ppc/spapr_pci.c
index 3d1145e..248f20a 100644
--- a/hw/ppc/spapr_pci.c
+++ b/hw/ppc/spapr_pci.c
@@ -803,6 +803,29 @@  static char *spapr_phb_get_loc_code(sPAPRPHBState *sphb, PCIDevice *pdev)
     return buf;
 }
 
+static int spapr_phb_dma_window_enable(sPAPRPHBState *sphb,
+                                       uint32_t liobn, uint32_t page_shift,
+                                       uint64_t window_addr,
+                                       uint64_t window_size)
+{
+    sPAPRTCETable *tcet;
+    uint32_t nb_table = window_size >> page_shift;
+
+    if (!nb_table) {
+        return -1;
+    }
+
+    tcet = spapr_tce_new_table(DEVICE(sphb), liobn, window_addr,
+                               page_shift, nb_table, false);
+    if (!tcet) {
+        return -1;
+    }
+
+    memory_region_add_subregion(&sphb->iommu_root, tcet->bus_offset,
+                                spapr_tce_get_iommu(tcet));
+    return 0;
+}
+
 /* Macros to operate with address in OF binding to PCI */
 #define b_x(x, p, l)    (((x) & ((1<<(l))-1)) << (p))
 #define b_n(x)          b_x((x), 31, 1) /* 0 if relocatable */
@@ -1228,8 +1251,6 @@  static void spapr_phb_realize(DeviceState *dev, Error **errp)
     int i;
     PCIBus *bus;
     uint64_t msi_window_size = 4096;
-    sPAPRTCETable *tcet;
-    uint32_t nb_table;
 
     if (sphb->index != (uint32_t)-1) {
         hwaddr windows_base;
@@ -1381,18 +1402,11 @@  static void spapr_phb_realize(DeviceState *dev, Error **errp)
         }
     }
 
-    nb_table = sphb->dma_win_size >> SPAPR_TCE_PAGE_SHIFT;
-    tcet = spapr_tce_new_table(DEVICE(sphb), sphb->dma_liobn,
-                               0, SPAPR_TCE_PAGE_SHIFT, nb_table, false);
-    if (!tcet) {
-        error_setg(errp, "Unable to create TCE table for %s",
-                   sphb->dtbusname);
-        return;
-    }
-
     /* Register default 32bit DMA window */
-    memory_region_add_subregion(&sphb->iommu_root, sphb->dma_win_addr,
-                                spapr_tce_get_iommu(tcet));
+    if (spapr_phb_dma_window_enable(sphb, sphb->dma_liobn, SPAPR_TCE_PAGE_SHIFT,
+                                    sphb->dma_win_addr, sphb->dma_win_size)) {
+        error_setg(errp, "Unable to create TCE table for %s", sphb->dtbusname);
+    }
 
     sphb->msi = g_hash_table_new_full(g_int_hash, g_int_equal, g_free, g_free);
 }