[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [Xen-devel] [PATCH QEMU-XEN v6 4/8] xen: Switch uses of
From: |
Andrew Cooper |
Subject: |
Re: [Qemu-devel] [Xen-devel] [PATCH QEMU-XEN v6 4/8] xen: Switch uses of xc_map_foreign_range into xc_map_foreign_pages |
Date: |
Wed, 9 Dec 2015 13:56:44 +0000 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Icedove/38.4.0 |
On 09/12/15 13:41, Ian Campbell wrote:
> On Thu, 2015-12-03 at 11:23 +0000, Ian Campbell wrote:
>> diff --git a/hw/display/xenfb.c b/hw/display/xenfb.c
>> index 5e324ef..c96d974 100644
>> --- a/hw/display/xenfb.c
>> +++ b/hw/display/xenfb.c
>> @@ -104,9 +104,8 @@ static int common_bind(struct common *c)
>> if (xenstore_read_fe_int(&c->xendev, "event-channel",
>> &c->xendev.remote_port) == -1)
>> return -1;
>>
>> - c->page = xc_map_foreign_range(xen_xc, c->xendev.dom,
>> - XC_PAGE_SIZE,
>> - PROT_READ | PROT_WRITE, mfn);
>> + c->page = xc_map_foreign_pages(xen_xc, c->xendev.dom,
>> + PROT_READ | PROT_WRITE, &mfn, 1);
> This doesn't build for i386 userspace, since mfn is a uint64_t but
> xc_map_foreign_pages() wants a xen_pfn_t * (where xen_pfn_t == unsigned
> long on x86).
>
> Until now that was just a truncation which was already checked for with:
>
> uint64_t mfn;
>
> if (xenstore_read_fe_uint64(&c->xendev, "page-ref", &mfn) == -1)
> return -1;
> assert(mfn == (xen_pfn_t)mfn);
>
> I think in principal passing "(xen_pfn_t *)&mfn" would ok (since it is a
> singleton array in this case), but I was thinking of going a bit further
> and:
It is never ok to convert a pointer like this. In 32bit (little endian)
userspace, it will leave the upper half of mfn uninitialised on the stack.
~Andrew
- [Qemu-devel] [PATCH QEMU-XEN v6 0/8] Begin to disentangle libxenctrl and provide some stable libraries, (continued)
- [Qemu-devel] [PATCH QEMU-XEN v6 0/8] Begin to disentangle libxenctrl and provide some stable libraries, Ian Campbell, 2015/12/03
- [Qemu-devel] [PATCH QEMU-XEN v6 1/8] xen_console: correctly cleanup primary console on teardown., Ian Campbell, 2015/12/03
- [Qemu-devel] [PATCH QEMU-XEN v6 2/8] xen: Switch to libxenevtchn interface for compat shims., Ian Campbell, 2015/12/03
- [Qemu-devel] [PATCH QEMU-XEN v6 7/8] xen: domainbuild: reopen libxenctrl interface after forking for domain watcher., Ian Campbell, 2015/12/03
- [Qemu-devel] [PATCH QEMU-XEN v6 3/8] xen: Switch to libxengnttab interface for compat shims., Ian Campbell, 2015/12/03
- [Qemu-devel] [PATCH QEMU-XEN v6 6/8] xen: Use stable library interfaces when they are available., Ian Campbell, 2015/12/03
- [Qemu-devel] [PATCH QEMU-XEN v6 4/8] xen: Switch uses of xc_map_foreign_range into xc_map_foreign_pages, Ian Campbell, 2015/12/03
- Re: [Qemu-devel] [PATCH QEMU-XEN v6 4/8] xen: Switch uses of xc_map_foreign_range into xc_map_foreign_pages, Stefano Stabellini, 2015/12/11
- Re: [Qemu-devel] [PATCH QEMU-XEN v6 4/8] xen: Switch uses of xc_map_foreign_range into xc_map_foreign_pages, Ian Campbell, 2015/12/11
- Re: [Qemu-devel] [PATCH QEMU-XEN v6 4/8] xen: Switch uses of xc_map_foreign_range into xc_map_foreign_pages, Stefano Stabellini, 2015/12/11
[Qemu-devel] [PATCH QEMU-XEN v6 5/8] xen: Switch uses of xc_map_foreign_{pages, bulk} to use libxenforeignmemory API., Ian Campbell, 2015/12/03
[Qemu-devel] [PATCH QEMU-XEN v6 8/8] xen: make it possible to build without the Xen PV domain builder, Ian Campbell, 2015/12/03
Re: [Qemu-devel] [Minios-devel] [PATCH v6 0/<VARIOUS>] Begin to disentangle libxenctrl and provide some stable libraries, Ian Campbell, 2015/12/09