| Message ID | 1479121286-6390-2-git-send-email-andrew.cooper3@citrix.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
>>> On 14.11.16 at 12:01, <andrew.cooper3@citrix.com> wrote: > Luckily, hvm_hypervisor_cpuid_leaf() and vmx_hypervisor_cpuid_leaf() are safe > to execute in the context of a PV guest, but HVM-specific feature flags > shouldn't be visible to PV guests. > > Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com> Reviewed-by: Jan Beulich <jbeulich@suse.com> albeit ... > --- a/xen/arch/x86/traps.c > +++ b/xen/arch/x86/traps.c > @@ -928,6 +928,11 @@ int cpuid_hypervisor_leaves( uint32_t idx, uint32_t sub_idx, > break; > > case 4: > + if ( !has_hvm_container_domain(currd) ) > + { > + *eax = *ebx = *ecx = *edx = 0; > + break; > + } > hvm_hypervisor_cpuid_leaf(sub_idx, eax, ebx, ecx, edx); > break; ... this being the last leaf, wouldn't we better limit the number of leaves (reported in leaf 0) to 3 for PV? Jan
On 14/11/16 11:38, Jan Beulich wrote: >>>> On 14.11.16 at 12:01, <andrew.cooper3@citrix.com> wrote: >> Luckily, hvm_hypervisor_cpuid_leaf() and vmx_hypervisor_cpuid_leaf() are safe >> to execute in the context of a PV guest, but HVM-specific feature flags >> shouldn't be visible to PV guests. >> >> Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com> > Reviewed-by: Jan Beulich <jbeulich@suse.com> > albeit ... > >> --- a/xen/arch/x86/traps.c >> +++ b/xen/arch/x86/traps.c >> @@ -928,6 +928,11 @@ int cpuid_hypervisor_leaves( uint32_t idx, uint32_t sub_idx, >> break; >> >> case 4: >> + if ( !has_hvm_container_domain(currd) ) >> + { >> + *eax = *ebx = *ecx = *edx = 0; >> + break; >> + } >> hvm_hypervisor_cpuid_leaf(sub_idx, eax, ebx, ecx, edx); >> break; > ... this being the last leaf, wouldn't we better limit the number of > leaves (reported in leaf 0) to 3 for PV? I considered this, but decided not to. The current max leaf handling is fragile, owing to some dubious control from the toolstack, and the existence of XEN_CPUID_MAX_NUM_LEAVES in the public API is absolutely broken. I am going to need to rework this all anyway, and its not clear whether we can/should report less than 4 leaves to PV guests. ~Andrew
diff --git a/xen/arch/x86/traps.c b/xen/arch/x86/traps.c index 14abb62..d56d76e 100644 --- a/xen/arch/x86/traps.c +++ b/xen/arch/x86/traps.c @@ -928,6 +928,11 @@ int cpuid_hypervisor_leaves( uint32_t idx, uint32_t sub_idx, break; case 4: + if ( !has_hvm_container_domain(currd) ) + { + *eax = *ebx = *ecx = *edx = 0; + break; + } hvm_hypervisor_cpuid_leaf(sub_idx, eax, ebx, ecx, edx); break;
Luckily, hvm_hypervisor_cpuid_leaf() and vmx_hypervisor_cpuid_leaf() are safe to execute in the context of a PV guest, but HVM-specific feature flags shouldn't be visible to PV guests. Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com> --- CC: Jan Beulich <JBeulich@suse.com> CC: Wei Liu <wei.liu2@citrix.com> --- xen/arch/x86/traps.c | 5 +++++ 1 file changed, 5 insertions(+)