[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v4 28/31] libxc/xen: introduce HVM_PARAM_CMDLINE_PFN
On 07/08/15 11:18, Roger Pau Monne wrote: > This HVM parameter returns a PFN that contains the address of the memory > page where the guest command line has been placed. > > Signed-off-by: Roger Pau Monnà <roger.pau@xxxxxxxxxx> > Cc: Ian Jackson <ian.jackson@xxxxxxxxxxxxx> > Cc: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx> > Cc: Ian Campbell <ian.campbell@xxxxxxxxxx> > Cc: Wei Liu <wei.liu2@xxxxxxxxxx> > Cc: Jan Beulich <jbeulich@xxxxxxxx> > Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx> > --- > tools/libxc/xc_dom_x86.c | 17 +++++++++++++++++ > xen/arch/x86/hvm/hvm.c | 2 ++ > xen/include/public/hvm/params.h | 5 ++++- > 3 files changed, 23 insertions(+), 1 deletion(-) > > diff --git a/tools/libxc/xc_dom_x86.c b/tools/libxc/xc_dom_x86.c > index 87bce6e..369745d 100644 > --- a/tools/libxc/xc_dom_x86.c > +++ b/tools/libxc/xc_dom_x86.c > @@ -562,6 +562,23 @@ static int alloc_magic_pages_hvm(struct xc_dom_image > *dom) > xc_hvm_param_set(xch, domid, HVM_PARAM_SHARING_RING_PFN, > special_pfn(SPECIALPAGE_SHARING)); > > + if ( dom->cmdline ) > + { > + xen_pfn_t cmdline_pfn = xc_dom_alloc_page(dom, "command line"); > + char *cmdline = xc_map_foreign_range(xch, domid, PAGE_SIZE, > + PROT_READ | PROT_WRITE, > + cmdline_pfn); > + if ( cmdline == NULL ) { Mix of coding styles. > + DOMPRINTF("Unable to map command line page"); > + goto error_out; > + } > + > + strncpy(cmdline, dom->cmdline, MAX_GUEST_CMDLINE); > + cmdline[MAX_GUEST_CMDLINE - 1] = '\0'; > + munmap(cmdline, PAGE_SIZE); > + xc_hvm_param_set(xch, domid, HVM_PARAM_CMDLINE_PFN, cmdline_pfn); I am still very much on the fence about the use of HVM parameters here, especially as this is one-shot information which will be freed by the guest boot process. How much of an inconvenience would it be to specify: %ebx is a phyaddr of a structure looking like: struct dmlike_start_info { uint32_t magic; uint32_t flags; /* so as not to shoot ourselves in the foot */ uint32_t cmdline_paddr; uint32_t nr_modules; uint32_t modlist_paddr; }; And a struct dmlite_modlist_entry { uint64_t paddr; uint64_t size; }; This avoids enforcing page alignment on the two bits of information. I don't forsee the structures needing to change in the future, and in the typical case can fit in a few hundred bytes rather than two pages. ~Andrew _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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