| Message ID | alpine.DEB.2.02.1404041520320.9060@kaball.uk.xensource.com |
|---|---|
| State | New |
| Headers | show |
>>> On 04.04.14 at 16:30, <stefano.stabellini@eu.citrix.com> wrote: > On Mon, 31 Mar 2014, Jan Beulich wrote: >> >>> On 28.03.14 at 19:00, <stefano.stabellini@eu.citrix.com> wrote: >> > I miss some context here. >> > What is the issue with xc_domain_pin_memory_cacheattr_range and how does >> > it affect QEMU (that uses the xc_domain_pin_memory_cacheattr variety)? >> >> The issue is that the hypervisor (and hence libxc) interface expect the >> passed range to be inclusive, yet the ending page number all the qemus >> pass is one past the intended range. > > Thanks for the clear explanation. > Is this patch what you are looking for? > > --- > > diff --git a/xen-all.c b/xen-all.c > index ba34739..027e7a8 100644 > --- a/xen-all.c > +++ b/xen-all.c > @@ -323,7 +323,7 @@ go_physmap: > > xc_domain_pin_memory_cacheattr(xen_xc, xen_domid, > start_addr >> TARGET_PAGE_BITS, > - (start_addr + size) >> TARGET_PAGE_BITS, > + (start_addr + size - 1) >> TARGET_PAGE_BITS, > XEN_DOMCTL_MEM_CACHEATTR_WB); > > snprintf(path, sizeof(path), Something along these lines, for all maintained trees. The main thing I'm not sure about is whether size can ever be zero, or not page aligned - in both cases further care would need to be taken. Jan
On Fri, 4 Apr 2014, Jan Beulich wrote: > >>> On 04.04.14 at 16:30, <stefano.stabellini@eu.citrix.com> wrote: > > On Mon, 31 Mar 2014, Jan Beulich wrote: > >> >>> On 28.03.14 at 19:00, <stefano.stabellini@eu.citrix.com> wrote: > >> > I miss some context here. > >> > What is the issue with xc_domain_pin_memory_cacheattr_range and how does > >> > it affect QEMU (that uses the xc_domain_pin_memory_cacheattr variety)? > >> > >> The issue is that the hypervisor (and hence libxc) interface expect the > >> passed range to be inclusive, yet the ending page number all the qemus > >> pass is one past the intended range. > > > > Thanks for the clear explanation. > > Is this patch what you are looking for? > > > > --- > > > > diff --git a/xen-all.c b/xen-all.c > > index ba34739..027e7a8 100644 > > --- a/xen-all.c > > +++ b/xen-all.c > > @@ -323,7 +323,7 @@ go_physmap: > > > > xc_domain_pin_memory_cacheattr(xen_xc, xen_domid, > > start_addr >> TARGET_PAGE_BITS, > > - (start_addr + size) >> TARGET_PAGE_BITS, > > + (start_addr + size - 1) >> TARGET_PAGE_BITS, > > XEN_DOMCTL_MEM_CACHEATTR_WB); > > > > snprintf(path, sizeof(path), > > Something along these lines, for all maintained trees. The main thing > I'm not sure about is whether size can ever be zero, or not page > aligned - in both cases further care would need to be taken. size cannot be zero, see: if (size <= 0) { return -1; } at the beginning of the function. Currently I don't think that size can be page misaligned. Even if it could I think that the above would do the right thing.
diff --git a/xen-all.c b/xen-all.c index ba34739..027e7a8 100644 --- a/xen-all.c +++ b/xen-all.c @@ -323,7 +323,7 @@ go_physmap: xc_domain_pin_memory_cacheattr(xen_xc, xen_domid, start_addr >> TARGET_PAGE_BITS, - (start_addr + size) >> TARGET_PAGE_BITS, + (start_addr + size - 1) >> TARGET_PAGE_BITS, XEN_DOMCTL_MEM_CACHEATTR_WB); snprintf(path, sizeof(path),