On Fri, 15 Jul 2022 18:16:26 +0100
Joao Martins <joao.m.martins@oracle.com> wrote:
> Calculate max *used* GPA against the CPU maximum possible address
> and error out if the former surprasses the latter. This ensures
> max used GPA is reacheable by configured phys-bits. Default phys-bits
> on Qemu is TCG_PHYS_ADDR_BITS (40) which is enough for the CPU to
> address 1Tb (0xff ffff ffff) or 1010G (0xfc ffff ffff) in AMD hosts
> with IOMMU.
>
> This is preparation for AMD guests with >1010G, where it will want relocate
> ram-above-4g to be after 1Tb instead of 4G.
>
> Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
Acked-by: Igor Mammedov <imammedo@redhat.com>
> ---
> hw/i386/pc.c | 27 +++++++++++++++++++++++++++
> 1 file changed, 27 insertions(+)
>
> diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> index cda435e3baeb..f30661b7f1a2 100644
> --- a/hw/i386/pc.c
> +++ b/hw/i386/pc.c
> @@ -880,6 +880,18 @@ static uint64_t pc_get_cxl_range_end(PCMachineState *pcms)
> return start;
> }
>
> +static hwaddr pc_max_used_gpa(PCMachineState *pcms, uint64_t pci_hole64_size)
> +{
> + X86CPU *cpu = X86_CPU(first_cpu);
> +
> + /* 32-bit systems don't have hole64 thus return max CPU address */
> + if (cpu->phys_bits <= 32) {
> + return ((hwaddr)1 << cpu->phys_bits) - 1;
> + }
> +
> + return pc_pci_hole64_start() + pci_hole64_size - 1;
> +}
> +
> void pc_memory_init(PCMachineState *pcms,
> MemoryRegion *system_memory,
> MemoryRegion *rom_memory,
> @@ -894,13 +906,28 @@ void pc_memory_init(PCMachineState *pcms,
> MachineClass *mc = MACHINE_GET_CLASS(machine);
> PCMachineClass *pcmc = PC_MACHINE_GET_CLASS(pcms);
> X86MachineState *x86ms = X86_MACHINE(pcms);
> + hwaddr maxphysaddr, maxusedaddr;
> hwaddr cxl_base, cxl_resv_end = 0;
> + X86CPU *cpu = X86_CPU(first_cpu);
>
> assert(machine->ram_size == x86ms->below_4g_mem_size +
> x86ms->above_4g_mem_size);
>
> linux_boot = (machine->kernel_filename != NULL);
>
> + /*
> + * phys-bits is required to be appropriately configured
> + * to make sure max used GPA is reachable.
> + */
> + maxusedaddr = pc_max_used_gpa(pcms, pci_hole64_size);
> + maxphysaddr = ((hwaddr)1 << cpu->phys_bits) - 1;
> + if (maxphysaddr < maxusedaddr) {
> + error_report("Address space limit 0x%"PRIx64" < 0x%"PRIx64
> + " phys-bits too low (%u)",
> + maxphysaddr, maxusedaddr, cpu->phys_bits);
> + exit(EXIT_FAILURE);
> + }
> +
> /*
> * Split single memory region and use aliases to address portions of it,
> * done for backwards compatibility with older qemus.