From: Jonathan Cameron <jonathan.came...@huawei.com> Once a read or write reaches a CXL type 3 device, the HDM decoders on the device are used to establish the Device Physical Address which should be accessed. These functions peform the required maths and then directly access the hostmem->mr to fullfil the actual operation. Note that failed writes are silent, but failed reads return poison. Note this is based loosely on:
https://lore.kernel.org/qemu-devel/20200817161853.593247-6-f4...@amsat.org/ [RFC PATCH 0/9] hw/misc: Add support for interleaved memory accesses Only lightly tested so far. More complex test cases yet to be written. Signed-off-by: Jonathan Cameron <jonathan.came...@huawei.com> --- hw/mem/cxl_type3.c | 81 +++++++++++++++++++++++++++++++++++++ include/hw/cxl/cxl_device.h | 5 +++ 2 files changed, 86 insertions(+) diff --git a/hw/mem/cxl_type3.c b/hw/mem/cxl_type3.c index e99d84c92d..eb0203dcbc 100644 --- a/hw/mem/cxl_type3.c +++ b/hw/mem/cxl_type3.c @@ -161,6 +161,87 @@ static void ct3_realize(PCIDevice *pci_dev, Error **errp) &ct3d->cxl_dstate.device_registers); } +/* TODO: Support multiple HDM decoders and DPA skip */ +static bool cxl_type3_dpa(CXLType3Dev *ct3d, hwaddr host_addr, uint64_t *dpa) +{ + uint32_t *cache_mem = ct3d->cxl_cstate.crb.cache_mem_registers; + uint64_t decoder_base, decoder_size, hpa_offset; + uint32_t hdm0_ctrl; + int ig, iw; + + decoder_base = (((uint64_t)cache_mem[R_CXL_HDM_DECODER0_BASE_HI] << 32) | + cache_mem[R_CXL_HDM_DECODER0_BASE_LO]); + if ((uint64_t)host_addr < decoder_base) { + return false; + } + + hpa_offset = (uint64_t)host_addr - decoder_base; + + decoder_size = ((uint64_t)cache_mem[R_CXL_HDM_DECODER0_SIZE_HI] << 32) | + cache_mem[R_CXL_HDM_DECODER0_SIZE_LO]; + if (hpa_offset >= decoder_size) { + return false; + } + + hdm0_ctrl = cache_mem[R_CXL_HDM_DECODER0_CTRL]; + iw = FIELD_EX32(hdm0_ctrl, CXL_HDM_DECODER0_CTRL, IW); + ig = FIELD_EX32(hdm0_ctrl, CXL_HDM_DECODER0_CTRL, IG); + + *dpa = (MAKE_64BIT_MASK(0, 8 + ig) & hpa_offset) | + ((MAKE_64BIT_MASK(8 + ig + iw, 64 - 8 - ig - iw) & hpa_offset) >> iw); + + return true; +} + +MemTxResult cxl_type3_read(PCIDevice *d, hwaddr host_addr, uint64_t *data, + unsigned size, MemTxAttrs attrs) +{ + CXLType3Dev *ct3d = CT3(d); + uint64_t dpa_offset; + MemoryRegion *mr; + + /* TODO support volatile region */ + mr = host_memory_backend_get_memory(ct3d->hostmem); + if (!mr) { + return MEMTX_ERROR; + } + + if (!cxl_type3_dpa(ct3d, host_addr, &dpa_offset)) { + return MEMTX_ERROR; + } + + if (dpa_offset > mr->size) { + return MEMTX_ERROR; + } + + return memory_region_dispatch_read(mr, dpa_offset, data, + size_memop(size), attrs); +} + +MemTxResult cxl_type3_write(PCIDevice *d, hwaddr host_addr, uint64_t data, + unsigned size, MemTxAttrs attrs) +{ + CXLType3Dev *ct3d = CT3(d); + uint64_t dpa_offset; + MemoryRegion *mr; + + mr = host_memory_backend_get_memory(ct3d->hostmem); + if (!mr) { + return MEMTX_OK; + } + + if (!cxl_type3_dpa(ct3d, host_addr, &dpa_offset)) { + return MEMTX_OK; + } + + if (dpa_offset > mr->size) { + return MEMTX_OK; + } + + return memory_region_dispatch_write(mr, dpa_offset, data, + size_memop(size), attrs); +} + static void ct3d_reset(DeviceState *dev) { CXLType3Dev *ct3d = CT3(dev); diff --git a/include/hw/cxl/cxl_device.h b/include/hw/cxl/cxl_device.h index 0426714e9b..0f6adbae32 100644 --- a/include/hw/cxl/cxl_device.h +++ b/include/hw/cxl/cxl_device.h @@ -258,4 +258,9 @@ struct CXLType3Class { uint64_t offset); }; +MemTxResult cxl_type3_read(PCIDevice *d, hwaddr host_addr, uint64_t *data, + unsigned size, MemTxAttrs attrs); +MemTxResult cxl_type3_write(PCIDevice *d, hwaddr host_addr, uint64_t data, + unsigned size, MemTxAttrs attrs); + #endif -- 2.32.0
