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From: | Alexey Kardashevskiy |
Subject: | Re: [Qemu-ppc] [PATCH qemu v13 02/16] spapr_pci: Move DMA window enablement to a helper |
Date: | Thu, 10 Mar 2016 16:47:04 +1100 |
User-agent: | Mozilla/5.0 (X11; Linux i686 on x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.6.0 |
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 <address@hidden> --- 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); }
-- Alexey
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