From: Mukesh Rathor Date: Wed, 13 Nov 2013 08:41:59 +0000 (+0100) Subject: pvh: documentation X-Git-Tag: archive/raspbian/4.8.0-1+rpi1~1^2~5960 X-Git-Url: https://dgit.raspbian.org/%22http:/www.example.com/cgi/%22https://%22%22/%22http:/www.example.com/cgi/%22https:/%22%22?a=commitdiff_plain;h=58076d00d89fdd040935a438efaec64f9665fbc4;p=xen.git pvh: documentation Signed-off-by: Mukesh Rathor Signed-off-by: George Dunlap Acked-by: Tim Deegan Acked-by: Keir Fraser Acked-by: Eddie Dong --- diff --git a/docs/misc/pvh-readme.txt b/docs/misc/pvh-readme.txt new file mode 100644 index 0000000000..9fea137f01 --- /dev/null +++ b/docs/misc/pvh-readme.txt @@ -0,0 +1,61 @@ + +PVH : an x86 PV guest running in an HVM container. + +See: http://blog.xen.org/index.php/2012/10/23/the-paravirtualization-spectrum-part-1-the-ends-of-the-spectrum/ + +At the moment HAP is required for PVH. + +At present the only PVH guest is an x86 64bit PV linux. Patches are at: + git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen.git + +A PVH guest kernel must support following features, as defined for linux +in arch/x86/xen/xen-head.S: + + #define FEATURES_PVH "|writable_descriptor_tables" \ + "|auto_translated_physmap" \ + "|supervisor_mode_kernel" \ + "|hvm_callback_vector" + +In a nutshell: +* the guest uses auto translate: + - p2m is managed by xen + - pagetables are owned by the guest + - mmu_update hypercall not available +* it uses event callback and not vlapic emulation, +* IDT is native, so set_trap_table hcall is also N/A for a PVH guest. + +For a full list of hcalls supported for PVH, see pvh_hypercall64_table +in arch/x86/hvm/hvm.c in xen. From the ABI prespective, it's mostly a +PV guest with auto translate, although it does use hvm_op for setting +callback vector, and has a special version of arch_set_guest_info for bringing +up secondary cpus. + +The initial phase targets the booting of a 64bit UP/SMP linux guest in PVH +mode. This is done by adding: pvh=1 in the config file. xl, and not xm, is +supported. Phase I patches are broken into three parts: + - xen changes for booting of 64bit PVH guest + - tools changes for creating a PVH guest + - boot of 64bit dom0 in PVH mode. + +Following fixme's exist in the code: + - arch/x86/time.c: support more tsc modes. + +Following remain to be done for PVH: + - Get rid of PVH mode, make it just HVM with some flags set + - implement arch_get_info_guest() for pvh. + - Investigate what else needs to be done for VMI support. + - AMD port. + - 32bit PVH guest support in both linux and xen. Xen changes are tagged + "32bitfixme". + - Add support for monitoring guest behavior. See hvm_memory_event* functions + in hvm.c + - vcpu hotplug support + - Live migration of PVH guests. + - Avail PVH dom0 of posted interrupts. (This will be a big win). + + +Note, any emails to me must be cc'd to xen devel mailing list. OTOH, please +cc me on PVH emails to the xen devel mailing list. + +Mukesh Rathor +mukesh.rathor [at] oracle [dot] com