On 1/2/21 11:44 AM, Philippe Mathieu-Daudé wrote:
> On 1/2/21 12:19 AM, Peter Maydell wrote:
>> On Fri, 1 Jan 2021 at 23:12, Philippe Mathieu-Daudé <f4...@amsat.org> wrote:
>>>
>>> Per the datasheet (Chapter 5.7.1. "PCI address regions"),
>>> the PCIMAP register:
>>>
>>> Map the 64Mbyte regions marked "PCI_Lo" in the CPU's memory map,
>>> each of which can be assigned to any 64 Mbyte-aligned region of
>>> PCI memory. The address appearing on the PCI bus consists of the
>>> low 26 bits of the CPU physical address, with the high 6 bits
>>> coming from the appropriate base6 field. Each of the three regions
>>> is an independent window onto PCI memory, and can be positioned on
>>> any 64Mbyte boundary in PCI space.
>>>
>>> Remap the 3 regions on reset and when PCIMAP is updated.
>>>
>>> Signed-off-by: Philippe Mathieu-Daudé <f4...@amsat.org>
>>> ---
>>> hw/pci-host/bonito.c | 49 ++++++++++++++++++++++++++++++++------------
>>> 1 file changed, 36 insertions(+), 13 deletions(-)
>>>
>>> diff --git a/hw/pci-host/bonito.c b/hw/pci-host/bonito.c
>>> index a99eced0657..c58eeaf504c 100644
>>> --- a/hw/pci-host/bonito.c
>>> +++ b/hw/pci-host/bonito.c
>>> @@ -137,6 +137,10 @@ FIELD(BONGENCFG, PCIQUEUE, 12, 1)
>>>
>>> /* 4. PCI address map control */
>>> #define BONITO_PCIMAP (0x10 >> 2) /* 0x110 */
>>> +FIELD(PCIMAP, LO0, 0, 6)
>>> +FIELD(PCIMAP, LO1, 6, 6)
>>> +FIELD(PCIMAP, LO2, 12, 6)
>>> +FIELD(PCIMAP, 2G, 18, 1)
>>> #define BONITO_PCIMEMBASECFG (0x14 >> 2) /* 0x114 */
>>> #define BONITO_PCIMAP_CFG (0x18 >> 2) /* 0x118 */
>>>
>>> @@ -237,6 +241,7 @@ struct BonitoState {
>>> qemu_irq *pic;
>>> PCIBonitoState *pci_dev;
>>> MemoryRegion pci_mem;
>>> + MemoryRegion pcimem_lo_alias[3];
>>> };
>>>
>>> #define TYPE_BONITO_PCI_HOST_BRIDGE "Bonito-pcihost"
>>> @@ -245,6 +250,31 @@ OBJECT_DECLARE_SIMPLE_TYPE(BonitoState,
>>> BONITO_PCI_HOST_BRIDGE)
>>> #define TYPE_PCI_BONITO "Bonito"
>>> OBJECT_DECLARE_SIMPLE_TYPE(PCIBonitoState, PCI_BONITO)
>>>
>>> +static void bonito_remap(PCIBonitoState *s)
>>> +{
>>> + static const char *const region_name[3] = {
>>> + "pci.lomem0", "pci.lomem1", "pci.lomem2"
>>> + };
>>> + BonitoState *bs = BONITO_PCI_HOST_BRIDGE(s->pcihost);
>>> +
>>> + for (size_t i = 0; i < 3; i++) {
>>> + uint32_t offset = extract32(s->regs[BONITO_PCIMAP], 6 * i, 6) <<
>>> 26;
>>> +
>>> + if (memory_region_is_mapped(&bs->pcimem_lo_alias[i])) {
>>> + memory_region_del_subregion(get_system_memory(),
>>> + &bs->pcimem_lo_alias[i]);
>>> + object_unparent(OBJECT(&bs->pcimem_lo_alias[i]));
>>> + }
>>> +
>>> + memory_region_init_alias(&bs->pcimem_lo_alias[i], OBJECT(s),
>>> + region_name[i], &bs->pci_mem,
>>> + offset, 64 * MiB);
>>> + memory_region_add_subregion(get_system_memory(),
>>> + BONITO_PCILO_BASE + i * 64 * MiB,
>>> + &bs->pcimem_lo_alias[i]);
>>> + }
>>
>> Rather than delete-and-reinit-and-add, it's probably better to
>> just create the subregions once at device startup, and then use
>> memory_region_set_enabled() and memory_region_set_address()
>> to manipulate whether the subregion is visible and what address
>> in the system memory it is mapped at.
>
> Great! Thanks Peter :) TIL these functions.
> From what I understand from memory_region_readd_subregion (called
> from memory_region_set_address) using memory_region_set_enabled()
> directly is enough.
Actually since this is a alias, we don't want to modify the base
address but the alias offset, so I need to use
memory_region_set_alias_offset().
