diff options
Diffstat (limited to 'hw/i386')
| -rw-r--r-- | hw/i386/pc.c | 54 |
1 files changed, 54 insertions, 0 deletions
diff --git a/hw/i386/pc.c b/hw/i386/pc.c index 56d8c179ea..1c5c9e17c6 100644 --- a/hw/i386/pc.c +++ b/hw/i386/pc.c @@ -891,6 +891,40 @@ static hwaddr pc_max_used_gpa(PCMachineState *pcms, uint64_t pci_hole64_size) return pc_pci_hole64_start() + pci_hole64_size - 1; } +/* + * AMD systems with an IOMMU have an additional hole close to the + * 1Tb, which are special GPAs that cannot be DMA mapped. Depending + * on kernel version, VFIO may or may not let you DMA map those ranges. + * Starting Linux v5.4 we validate it, and can't create guests on AMD machines + * with certain memory sizes. It's also wrong to use those IOVA ranges + * in detriment of leading to IOMMU INVALID_DEVICE_REQUEST or worse. + * The ranges reserved for Hyper-Transport are: + * + * FD_0000_0000h - FF_FFFF_FFFFh + * + * The ranges represent the following: + * + * Base Address Top Address Use + * + * FD_0000_0000h FD_F7FF_FFFFh Reserved interrupt address space + * FD_F800_0000h FD_F8FF_FFFFh Interrupt/EOI IntCtl + * FD_F900_0000h FD_F90F_FFFFh Legacy PIC IACK + * FD_F910_0000h FD_F91F_FFFFh System Management + * FD_F920_0000h FD_FAFF_FFFFh Reserved Page Tables + * FD_FB00_0000h FD_FBFF_FFFFh Address Translation + * FD_FC00_0000h FD_FDFF_FFFFh I/O Space + * FD_FE00_0000h FD_FFFF_FFFFh Configuration + * FE_0000_0000h FE_1FFF_FFFFh Extended Configuration/Device Messages + * FE_2000_0000h FF_FFFF_FFFFh Reserved + * + * See AMD IOMMU spec, section 2.1.2 "IOMMU Logical Topology", + * Table 3: Special Address Controls (GPA) for more information. + */ +#define AMD_HT_START 0xfd00000000UL +#define AMD_HT_END 0xffffffffffUL +#define AMD_ABOVE_1TB_START (AMD_HT_END + 1) +#define AMD_HT_SIZE (AMD_ABOVE_1TB_START - AMD_HT_START) + void pc_memory_init(PCMachineState *pcms, MemoryRegion *system_memory, MemoryRegion *rom_memory, @@ -915,6 +949,26 @@ void pc_memory_init(PCMachineState *pcms, linux_boot = (machine->kernel_filename != NULL); /* + * The HyperTransport range close to the 1T boundary is unique to AMD + * hosts with IOMMUs enabled. Restrict the ram-above-4g relocation + * to above 1T to AMD vCPUs only. + */ + if (IS_AMD_CPU(&cpu->env)) { + /* Bail out if max possible address does not cross HT range */ + if (pc_max_used_gpa(pcms, pci_hole64_size) >= AMD_HT_START) { + x86ms->above_4g_mem_start = AMD_ABOVE_1TB_START; + } + + /* + * Advertise the HT region if address space covers the reserved + * region or if we relocate. + */ + if (cpu->phys_bits >= 40) { + e820_add_entry(AMD_HT_START, AMD_HT_SIZE, E820_RESERVED); + } + } + + /* * phys-bits is required to be appropriately configured * to make sure max used GPA is reachable. */ |