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Re: [Qemu-devel] [PATCH v3 2/2] Xen: Use the ioreq-server API when avail
From: |
Peter Maydell |
Subject: |
Re: [Qemu-devel] [PATCH v3 2/2] Xen: Use the ioreq-server API when available |
Date: |
Wed, 15 Oct 2014 19:30:25 +0200 |
On 15 October 2014 11:16, Paul Durrant <address@hidden> wrote:
> The ioreq-server API added to Xen 4.5 offers better security than
> the existing Xen/QEMU interface because the shared pages that are
> used to pass emulation request/results back and forth are removed
> from the guest's memory space before any requests are serviced.
> This prevents the guest from mapping these pages (they are in a
> well known location) and attempting to attack QEMU by synthesizing
> its own request structures. Hence, this patch modifies configure
> to detect whether the API is available, and adds the necessary
> code to use the API if it is.
This commit message doesn't mention it, but presumably this is
all x86-specific given it's in a file which is only used for
x86 Xen?
> +static void xen_hvm_pre_save(void *opaque)
> +{
> + XenIOState *state = opaque;
> +
> + /* Stop servicing emulation requests */
> + xen_set_ioreq_server_state(xen_xc, xen_domid, state->ioservid, 0);
> + xen_destroy_ioreq_server(xen_xc, xen_domid, state->ioservid);
> +}
> +
> +static const VMStateDescription vmstate_xen_hvm = {
> + .name = "xen-hvm",
> + .version_id = 4,
> + .minimum_version_id = 4,
This is new in upstream so why's it starting at version 4?
> + .pre_save = xen_hvm_pre_save,
> + .fields = (VMStateField[]) {
> + VMSTATE_END_OF_LIST()
> + },
A vmstate which doesn't actually save any state? This seems
rather suspicious...
> @@ -1060,12 +1185,19 @@ int xen_hvm_init(ram_addr_t *below_4g_mem_size,
> ram_addr_t *above_4g_mem_size,
> xen_ram_init(below_4g_mem_size, above_4g_mem_size, ram_size, ram_memory);
>
> qemu_add_vm_change_state_handler(xen_hvm_change_state_handler, state);
> + vmstate_register(NULL, 0, &vmstate_xen_hvm, state);
Is the new use of vmstate_register() really necessary?
Usually the state you're saving corresponds to some QOM
device whose vmsd field you can use instead.
thanks
-- PMM
- Re: [Qemu-devel] [PATCH v3 1/2] Add device listener interface, (continued)
[Qemu-devel] [PATCH v3 2/2] Xen: Use the ioreq-server API when available, Paul Durrant, 2014/10/15
Re: [Qemu-devel] [PATCH v3 2/2] Xen: Use the ioreq-server API when available, Paul Durrant, 2014/10/16
Re: [Qemu-devel] [PATCH v3 2/2] Xen: Use the ioreq-server API when available, Stefano Stabellini, 2014/10/16
Re: [Qemu-devel] [PATCH v3 2/2] Xen: Use the ioreq-server API when available,
Peter Maydell <=
- Re: [Qemu-devel] [PATCH v3 2/2] Xen: Use the ioreq-server API when available, Paolo Bonzini, 2014/10/16
- Re: [Qemu-devel] [PATCH v3 2/2] Xen: Use the ioreq-server API when available, Paul Durrant, 2014/10/16
- Re: [Qemu-devel] [PATCH v3 2/2] Xen: Use the ioreq-server API when available, Paolo Bonzini, 2014/10/16
- Re: [Qemu-devel] [PATCH v3 2/2] Xen: Use the ioreq-server API when available, Paul Durrant, 2014/10/16
- Re: [Qemu-devel] [PATCH v3 2/2] Xen: Use the ioreq-server API when available, Paolo Bonzini, 2014/10/16
Re: [Qemu-devel] [PATCH v3 2/2] Xen: Use the ioreq-server API when available, Paul Durrant, 2014/10/16
Re: [Qemu-devel] [PATCH v3 2/2] Xen: Use the ioreq-server API when available, Paul Durrant, 2014/10/16
Re: [Qemu-devel] [PATCH v3 2/2] Xen: Use the ioreq-server API when available, Stefano Stabellini, 2014/10/16
Re: [Qemu-devel] [PATCH v3 2/2] Xen: Use the ioreq-server API when available, Peter Maydell, 2014/10/16
Re: [Qemu-devel] [PATCH v3 2/2] Xen: Use the ioreq-server API when available, Stefano Stabellini, 2014/10/16