On 08.11.23 12:17, Nicolas Saenz Julienne wrote:
Introduce two helper functions. The first one queries a vCPU's VTL
level, the second one, given a struct kvm_vcpu and VTL pair, returns the
corresponding 'sibling' struct kvm_vcpu at the right VTL.

We keep track of each VTL's state by having a distinct struct kvm_vpcu
for each level. VTL-vCPUs that belong to the same guest CPU share the
same physical APIC id, but belong to different APIC groups where the
apic group represents the vCPU's VTL.

Signed-off-by: Nicolas Saenz Julienne <nsa...@amazon.com>
  arch/x86/kvm/hyperv.h | 18 ++++++++++++++++++
  1 file changed, 18 insertions(+)

diff --git a/arch/x86/kvm/hyperv.h b/arch/x86/kvm/hyperv.h
index 2bfed69ba0db..5433107e7cc8 100644
--- a/arch/x86/kvm/hyperv.h
+++ b/arch/x86/kvm/hyperv.h
@@ -23,6 +23,7 @@
#include <linux/kvm_host.h>
  #include "x86.h"
+#include "lapic.h"
/* "Hv#1" signature */
  #define HYPERV_CPUID_SIGNATURE_EAX 0x31237648
@@ -83,6 +84,23 @@ static inline struct kvm_hv_syndbg *to_hv_syndbg(struct 
kvm_vcpu *vcpu)
        return &vcpu->kvm->arch.hyperv.hv_syndbg;
+static inline struct kvm_vcpu *kvm_hv_get_vtl_vcpu(struct kvm_vcpu *vcpu, int vtl)
+       struct kvm *kvm = vcpu->kvm;
+       u32 target_id = kvm_apic_id(vcpu);
+       kvm_apic_id_set_group(kvm, vtl, &target_id);
+       if (vcpu->vcpu_id == target_id)
+               return vcpu;
+       return kvm_get_vcpu_by_id(kvm, target_id);
+static inline u8 kvm_hv_get_active_vtl(struct kvm_vcpu *vcpu)
+       return kvm_apic_group(vcpu);

Shouldn't this check whether VTL is active? If someone wants to use APIC groups for a different purpose in the future, they'd suddenly find themselves in VTL code paths in other code (such as memory protections), no?


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