Re: [PATCH] virtio: Define and use per-architecture pfn shift constants
Hollis Blanchard wrote: # HG changeset patch # User Hollis Blanchard [EMAIL PROTECTED] # Date 1225946980 21600 # Node ID f58566dfe20e841604e1377ff41e9e0501c1cf18 # Parent f776b102380286dd173a3b89f7dc976140812517 virtio: Define and use per-architecture pfn shift constants Both sides of the virtio interface must agree about how big a pfn really is. This is particularly an issue on architectures where the page size is configurable (e.g. PowerPC, IA64) -- the interface must be independent of PAGE_SHIFT. This patch should have no functional effect on x86 or ia64, but an ack from the IA64 guys would be good because I'm not clear on their page size requirements. Signed-off-by: Hollis Blanchard [EMAIL PROTECTED] Acked-by: Anthony Liguori [EMAIL PROTECTED] Regards, Anthony Liguori -- To unsubscribe from this list: send the line unsubscribe kvm-ppc in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH] virtio: Define and use per-architecture pfn shift constants
On Thu, 2008-11-06 at 10:49 +, Mark McLoughlin wrote: On Wed, 2008-11-05 at 22:49 -0600, Hollis Blanchard wrote: - info-queue = kzalloc(PAGE_ALIGN(vring_size(num,PAGE_SIZE)), GFP_KERNEL); + vring_bytes = PAGE_ALIGN(vring_size(num, VRING_PAGE_SIZE)); + info-queue = kzalloc(vring_bytes, GFP_KERNEL); You're still aligning the size to PAGE_SIZE rather than VRING_PAGE_SIZE? The original code was calling kzalloc with a multiple of PAGE_SIZE, so I kept that behavior here... But actually, why do we align the size anyway? I assume it's so that the last page in the ring (containing the used fields) could be safely mapped into another guest's address space, without fear of exposing other data. I don't know how valuable that is, but that's not really my concern so I preserved the behavior. Also might make sense for vring_init() and vring_size() not to take a pagesize argument and hard-code them to use VRING_PAGE_SIZE. I think that's a good idea. Anthony mentioned earlier the code was done this way so it could be copied to userspace, where PAGE_SIZE is unavailable, but that isn't an issue if we switch to VRING_PAGE_SIZE. -- Hollis Blanchard IBM Linux Technology Center -- To unsubscribe from this list: send the line unsubscribe kvm-ppc in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH] virtio: Define and use per-architecture pfn shift constants
Hollis Blanchard wrote: On Thu, 2008-11-06 at 10:49 +, Mark McLoughlin wrote: But actually, why do we align the size anyway? I assume it's so that the last page in the ring (containing the used fields) could be safely mapped into another guest's address space, without fear of exposing other data. I don't know how valuable that is, but that's not really my concern so I preserved the behavior. Also might make sense for vring_init() and vring_size() not to take a pagesize argument and hard-code them to use VRING_PAGE_SIZE. I think that's a good idea. Anthony mentioned earlier the code was done this way so it could be copied to userspace, where PAGE_SIZE is unavailable, but that isn't an issue if we switch to VRING_PAGE_SIZE. Agreed. Regards, Anthony Liguori -- To unsubscribe from this list: send the line unsubscribe kvm-ppc in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH] virtio: Define and use per-architecture pfn shift constants
Hollis Blanchard wrote: # HG changeset patch # User Hollis Blanchard [EMAIL PROTECTED] # Date 1225946980 21600 # Node ID f58566dfe20e841604e1377ff41e9e0501c1cf18 # Parent f776b102380286dd173a3b89f7dc976140812517 virtio: Define and use per-architecture pfn shift constants Both sides of the virtio interface must agree about how big a pfn really is. This is particularly an issue on architectures where the page size is configurable (e.g. PowerPC, IA64) -- the interface must be independent of PAGE_SHIFT. This patch should have no functional effect on x86 or ia64, but an ack from the IA64 guys would be good because I'm not clear on their page size requirements. Signed-off-by: Hollis Blanchard [EMAIL PROTECTED] This is missing a fix for virtio-balloon. Regards, Anthony Liguori -- To unsubscribe from this list: send the line unsubscribe kvm-ppc in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
