Messages in this thread | | | Subject | Re: [PATCH v2 5/7] x86/xen: nopv parameter support for HVM guest | From | Juergen Gross <> | Date | Wed, 26 Jun 2019 11:03:25 +0200 |
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On 26.06.19 10:56, Zhenzhong Duan wrote: > > On 2019/6/25 20:31, Juergen Gross wrote: >> On 24.06.19 14:02, Zhenzhong Duan wrote: >>> PVH guest needs PV extentions to work, so nopv parameter is ignored >>> for PVH but not for HVM guest. >>> >>> In order for nopv parameter to take effect for HVM guest, we need to >>> distinguish between PVH and HVM guest early in hypervisor detection >>> code. By moving the detection of PVH in xen_platform_hvm(), >>> xen_pvh_domain() could be used for that purpose. >>> >>> Signed-off-by: Zhenzhong Duan <zhenzhong.duan@oracle.com> >>> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> >>> Cc: Juergen Gross <jgross@suse.com> >>> Cc: Stefano Stabellini <sstabellini@kernel.org> >>> Cc: Thomas Gleixner <tglx@linutronix.de> >>> Cc: Ingo Molnar <mingo@redhat.com> >>> Cc: Borislav Petkov <bp@alien8.de> >>> Cc: xen-devel@lists.xenproject.org >>> --- >>> arch/x86/xen/enlighten_hvm.c | 18 ++++++++++++------ >>> 1 file changed, 12 insertions(+), 6 deletions(-) >>> >>> diff --git a/arch/x86/xen/enlighten_hvm.c b/arch/x86/xen/enlighten_hvm.c >>> index 7fcb4ea..26939e7 100644 >>> --- a/arch/x86/xen/enlighten_hvm.c >>> +++ b/arch/x86/xen/enlighten_hvm.c >>> @@ -25,6 +25,7 @@ >>> #include "mmu.h" >>> #include "smp.h" >>> +extern bool nopv; >>> static unsigned long shared_info_pfn; >>> void xen_hvm_init_shared_info(void) >>> @@ -226,20 +227,24 @@ static uint32_t __init xen_platform_hvm(void) >>> if (xen_pv_domain()) >>> return 0; >>> +#ifdef CONFIG_XEN_PVH >>> + /* Test for PVH domain (PVH boot path taken overrides ACPI >>> flags). */ >>> + if (!x86_platform.legacy.rtc && x86_platform.legacy.no_vga) >>> + xen_pvh = true; >> >> Sorry, this won't work, as ACPI tables are scanned only some time later. > Hmm, right. Thanks for point out. >> >> You can test for xen_pvh being true here (for the case where the guest >> has been booted via the Xen-PVH boot entry) and handle that case, but >> the case of a PVH guest started via the normal boot entry (like via >> grub2) and nopv specified is difficult. The only idea I have right now >> would be to use another struct hypervisor_x86 for that case which will >> only be used for Xen HVM/PVH _and_ nopv specified. It should be a copy >> of the bare metal variant, but a special guest_late_init member issuing >> a big fat warning in case PVH is being detected. > > After that warning, I guess PVH will run into hang finally? If it's > true, BUG() is better? > > Adding another hypervisor_x86 is a bit redundant, I think of below change. > > I'll test it tomorrow. But appreciate your suggestion whether it's > feasible. Thanks
Yes, this seems to be a viable option.
> > --- a/arch/x86/xen/enlighten_hvm.c > +++ b/arch/x86/xen/enlighten_hvm.c > @@ -25,6 +25,7 @@ > #include "mmu.h" > #include "smp.h" > > +extern bool nopv; > static unsigned long shared_info_pfn; > > void xen_hvm_init_shared_info(void) > @@ -221,11 +222,37 @@ bool __init xen_hvm_need_lapic(void) > return true; > } > > +static __init void xen_hvm_nopv_guest_late_init(void) > +{ > +#ifdef CONFIG_XEN_PVH > + if (x86_platform.legacy.rtc || !x86_platform.legacy.no_vga) > + return; > + > + /* PVH detected. */ > + xen_pvh = true; > + > + printk(KERN_CRIT "nopv parameter isn't supported in PVH guest\n"); > + BUG(); > +#endif > +} > + > + > static uint32_t __init xen_platform_hvm(void) > { > if (xen_pv_domain()) > return 0; > > + if (xen_pvh_domain() && nopv) > + { > + /* guest booting via the Xen-PVH boot entry goes here */
Mind adjusting indentation of that comment?
> + printk(KERN_INFO "nopv parameter is ignored in PVH > guest\n"); > + } > + else if (nopv) > + { > + /* guest booting via normal boot entry (like via grub2) goes > here */
Same again?
With those corrected and no other changes you can add my:
Reviewed-by: Juergen Gross <jgross@suse.com>
Juergen
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