Merge tag 'kvm-x86-xen-6.15' of https://github.com/kvm-x86/linux into HEAD

KVM Xen changes for 6.15

 - Don't write to the Xen hypercall page on MSR writes that are initiated by
   the host (userspace or KVM) to fix a class of bugs where KVM can write to
   guest memory at unexpected times, e.g. during vCPU creation if userspace has
   set the Xen hypercall MSR index to collide with an MSR that KVM emulates.

 - Restrict the Xen hypercall MSR indx to the unofficial synthetic range to
   reduce the set of possible collisions with MSRs that are emulated by KVM
   (collisions can still happen as KVM emulates Hyper-V MSRs, which also reside
   in the synthetic range).

 - Clean up and optimize KVM's handling of Xen MSR writes and xen_hvm_config.

 - Update Xen TSC leaves during CPUID emulation instead of modifying the CPUID
   entries when updating PV clocks, as there is no guarantee PV clocks will be
   updated between TSC frequency changes and CPUID emulation, and guest reads
   of Xen TSC should be rare, i.e. are not a hot path.

1 files changed, 3 insertions, 0 deletions

diff --git a/arch/x86/include/uapi/asm/kvm.h b/arch/x86/include/uapi/asm/kvm.h
index 9e75da97bce0..460306b35a4b 100644
--- a/arch/x86/include/uapi/asm/kvm.h
+++ b/arch/x86/include/uapi/asm/kvm.h
@@ -559,6 +559,9 @@ struct kvm_x86_mce {
 #define KVM_XEN_HVM_CONFIG_PVCLOCK_TSC_UNSTABLE	(1 << 7)
 #define KVM_XEN_HVM_CONFIG_SHARED_INFO_HVA	(1 << 8)
 
+#define KVM_XEN_MSR_MIN_INDEX			0x40000000u
+#define KVM_XEN_MSR_MAX_INDEX			0x4fffffffu
+
 struct kvm_xen_hvm_config {
 	__u32 flags;
 	__u32 msr;