Re: [PATCH] hw/display/qxl: Set pci rom address aligned with page size

[maobibo]

Sorry I do not state the background clearly.

Page size is 16K on my MIPS machine, and it supports running
guest OS in kvm mode and qxl vga card can used for VM. Qxl pci
rom size is 8K, smaller than 16K page size on host system, it
fails to be added into  memslot in kvm mode since size of
the pci memory space is not page aligned. Here is code in linux,
it requires memory_size and guest_phys_addr is page size aligned.

int __kvm_set_memory_region(struct kvm *kvm,
                            const struct kvm_userspace_memory_region *mem)
{
        struct kvm_memory_slot old, new;
        struct kvm_memory_slot *tmp;
        enum kvm_mr_change change;
        int as_id, id;
        int r;

        r = check_memory_region_flags(mem);
        if (r)
                return r;

        as_id = mem->slot >> 16;
        id = (u16)mem->slot;

        /* General sanity checks */
        if (mem->memory_size & (PAGE_SIZE - 1))
                return -EINVAL;
        if (mem->guest_phys_addr & (PAGE_SIZE - 1))
                return -EINVAL;


regards
bibo, mao

在 2021年05月17日 15:19, Gerd Hoffmann 写道:
> On Sat, May 15, 2021 at 04:06:23PM +0800, Bibo Mao wrote:
>> From: maobibo <maobibo@loongson.cn>
>>
>> pci memory bar size should be aligned with page size, else it will
>> not be effective memslot when running in kvm mode.
>>
>> This patch set qxl pci rom size aligned with page size of host
>> machine.
> 
> What is the exact problem you are trying to fix here?
> 
> take care,
>   Gerd
>