Messages in this thread Patch in this message | | | Subject | Re: [PATCH v2 5/7] x86/xen: nopv parameter support for HVM guest | From | Zhenzhong Duan <> | Date | Wed, 26 Jun 2019 16:56:46 +0800 |
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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
--- 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 */ + 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 */ + x86_init.hyper.guest_late_init = xen_hvm_nopv_guest_late_init; + return 0; + } return xen_cpuid_base(); }
@@ -258,4 +285,5 @@ static __init void xen_hvm_guest_late_init(void) .init.init_mem_mapping = xen_hvm_init_mem_mapping, .init.guest_late_init = xen_hvm_guest_late_init, .runtime.pin_vcpu = xen_pin_vcpu, + .ignore_nopv = true, };
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