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Re: [Qemu-devel] Help writing a trivial device
From: |
Stefan Hajnoczi |
Subject: |
Re: [Qemu-devel] Help writing a trivial device |
Date: |
Tue, 27 Sep 2011 08:08:02 +0100 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Mon, Sep 26, 2011 at 08:03:12PM +0200, Lluís Vilanova wrote:
> #if 1 /* KVM doesn't like it */
> s->data_ptr = g_malloc(s->size);
> memory_region_init_ram_ptr(&s->data, &s->dev.qdev, "backdoor.data",
> s->size, s->data_ptr);
> pci_register_bar(&s->dev, 1, PCI_BASE_ADDRESS_SPACE_MEMORY, &s->data);
> #endif
Have you tried page-aligning data_ptr with qemu_memalign() or doing an
anonymous mmap instead of g_malloc()?
>From virt/kvm/kvm_main.c:__kvm_set_memory_region():
/* General sanity checks */
if (mem->memory_size & (PAGE_SIZE - 1))
goto out;
if (mem->guest_phys_addr & (PAGE_SIZE - 1))
goto out;
/* We can read the guest memory with __xxx_user() later on. */
if (user_alloc &&
((mem->userspace_addr & (PAGE_SIZE - 1)) ||
!access_ok(VERIFY_WRITE,
(void __user *)(unsigned long)mem->userspace_addr,
mem->memory_size)))
goto out;
Stefan
Re: [Qemu-devel] Help writing a trivial device, Zhi Yong Wu, 2011/09/27