linux-kernel - Re: [PATCH v9 03/19] KVM: selftests: Expose functions to get default sregs values

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Message-ID: <aK2_GMSYuPCXe1A6@google.com>
Date: Tue, 26 Aug 2025 07:05:12 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Binbin Wu <binbin.wu@...ux.intel.com>
Cc: Sagi Shahar <sagis@...gle.com>, linux-kselftest@...r.kernel.org, 
	Paolo Bonzini <pbonzini@...hat.com>, Shuah Khan <shuah@...nel.org>, 
	Ackerley Tng <ackerleytng@...gle.com>, Ryan Afranji <afranji@...gle.com>, 
	Andrew Jones <ajones@...tanamicro.com>, Isaku Yamahata <isaku.yamahata@...el.com>, 
	Erdem Aktas <erdemaktas@...gle.com>, Rick Edgecombe <rick.p.edgecombe@...el.com>, 
	Roger Wang <runanwang@...gle.com>, Oliver Upton <oliver.upton@...ux.dev>, 
	"Pratik R. Sampat" <pratikrajesh.sampat@....com>, Reinette Chatre <reinette.chatre@...el.com>, 
	Ira Weiny <ira.weiny@...el.com>, Chao Gao <chao.gao@...el.com>, 
	Chenyi Qiang <chenyi.qiang@...el.com>, linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Subject: Re: [PATCH v9 03/19] KVM: selftests: Expose functions to get default
 sregs values

On Tue, Aug 26, 2025, Binbin Wu wrote:
> On 8/21/2025 12:28 PM, Sagi Shahar wrote:
> > TDX can't set sregs values directly using KVM_SET_SREGS. Expose the
> > default values of certain sregs used by TDX VMs so they can be set
> > manually.
> > 
> > Signed-off-by: Sagi Shahar <sagis@...gle.com>
> > ---
> >   .../selftests/kvm/include/x86/processor.h     |  6 +++
> >   .../testing/selftests/kvm/lib/x86/processor.c | 41 +++++++++++++++----
> >   2 files changed, 40 insertions(+), 7 deletions(-)
> > 
> > diff --git a/tools/testing/selftests/kvm/include/x86/processor.h b/tools/testing/selftests/kvm/include/x86/processor.h
> > index 2efb05c2f2fb..5c16507f9b2d 100644
> > --- a/tools/testing/selftests/kvm/include/x86/processor.h
> > +++ b/tools/testing/selftests/kvm/include/x86/processor.h
> > @@ -1026,6 +1026,12 @@ static inline struct kvm_cpuid2 *allocate_kvm_cpuid2(int nr_entries)
> >   void vcpu_init_cpuid(struct kvm_vcpu *vcpu, const struct kvm_cpuid2 *cpuid);
> > +uint16_t kvm_get_default_idt_limit(void);
> > +uint16_t kvm_get_default_gdt_limit(void);
> > +uint64_t kvm_get_default_cr0(void);
> > +uint64_t kvm_get_default_cr4(void);
> > +uint64_t kvm_get_default_efer(void);
> Can these be defined in the header file as static inline?

Yes please.  Performance isn't a concern, but as a developer, it's nice to not
have to bounce to a definition to find such simple information.