| Message ID | 20170629172647.22188-2-rkrcmar@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thu, Jun 29, 2017 at 10:26 AM, Radim Krčmář <rkrcmar@redhat.com> wrote: > > Reading the memory mapped page with x2apic is a bug. Use the generic reader > instead. An alternative would be to disable x2apic. > > Signed-off-by: Radim Krčmář <rkrcmar@redhat.com> Reviewed-by: Peter Feiner <pfeiner@google.com> > --- > x86/vmx_tests.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/x86/vmx_tests.c b/x86/vmx_tests.c > index 1f439522cad8..7be016ce4fbc 100644 > --- a/x86/vmx_tests.c > +++ b/x86/vmx_tests.c > @@ -1031,7 +1031,7 @@ static int ept_init_common(bool have_ad) > install_ept(pml4, (unsigned long)data_page1, (unsigned long)data_page2, > EPT_RA | EPT_WA | EPT_EA); > > - apic_version = *((u32 *)0xfee00030UL); > + apic_version = apic_read(APIC_LVR); > return VMX_TEST_START; > } > > -- > 2.13.2 > Looks good!
On 29/06/2017 19:34, Peter Feiner wrote: > Reading the memory mapped page with x2apic is a bug. Use the generic reader > instead. An alternative would be to disable x2apic. Disabling x2apic would test what the test is supposed to test. :) Paolo
2017-06-30 12:22+0200, Paolo Bonzini: > On 29/06/2017 19:34, Peter Feiner wrote: > > Reading the memory mapped page with x2apic is a bug. Use the generic reader > > instead. An alternative would be to disable x2apic. > > Disabling x2apic would test what the test is supposed to test. :) We should still be doing the same -- we're interested in testing the MMIO access from the guest, which is being done in ept_main(). ept_init_common() is used just to access the reference value and I think that allowing x2APIC there gives us a bit more leeway, thanks.
----- Original Message ----- > From: "Radim Krčmář" <rkrcmar@redhat.com> > To: "Paolo Bonzini" <pbonzini@redhat.com> > Cc: "Peter Feiner" <pfeiner@google.com>, kvm@vger.kernel.org, "David Matlack" <dmatlack@google.com> > Sent: Monday, July 3, 2017 7:13:44 PM > Subject: Re: [kvm-unit-tests PATCH 1/3] x86/vmx: fix EPT - MMIO access > > 2017-06-30 12:22+0200, Paolo Bonzini: > > On 29/06/2017 19:34, Peter Feiner wrote: > > > Reading the memory mapped page with x2apic is a bug. Use the generic > > > reader > > > instead. An alternative would be to disable x2apic. > > > > Disabling x2apic would test what the test is supposed to test. :) > > We should still be doing the same -- we're interested in testing the > MMIO access from the guest, which is being done in ept_main(). > > ept_init_common() is used just to access the reference value and I think > that allowing x2APIC there gives us a bit more leeway, Thanks for the explanation. You're obviously right, will apply tomorrow with an improved commit message. Paolo
diff --git a/x86/vmx_tests.c b/x86/vmx_tests.c index 1f439522cad8..7be016ce4fbc 100644 --- a/x86/vmx_tests.c +++ b/x86/vmx_tests.c @@ -1031,7 +1031,7 @@ static int ept_init_common(bool have_ad) install_ept(pml4, (unsigned long)data_page1, (unsigned long)data_page2, EPT_RA | EPT_WA | EPT_EA); - apic_version = *((u32 *)0xfee00030UL); + apic_version = apic_read(APIC_LVR); return VMX_TEST_START; }
Reading the memory mapped page with x2apic is a bug. Use the generic reader instead. An alternative would be to disable x2apic. Signed-off-by: Radim Krčmář <rkrcmar@redhat.com> --- x86/vmx_tests.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)