Re: [PATCH v3 30/40] KVM: x86: Move MSR helper declarations from kvm_host.h => msrs.h

[Huang, Kai]

On Fri, 2026-05-29 at 15:22 -0700, Sean Christopherson wrote:
> Relocate declarations of MSR helpers (and kvm_nr_uret_msrs) from x86's
> x86's kvm_host.h to msrs, to continue trimming down kvm_host.h.

Double x86's

> 
> Deliberately leave the funky read_msr() where it is, as it will hopefully
> be removed entirely as part of a broader kernel-API cleanup.
> 
> No functional change intended.
> 
> Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>

Reviewed-by: Kai Huang <kai.huang@xxxxxxxxx>

Btw, not sure whether you like:

We can also move the body of 'struct msr_bitmap_range' and 'struct
kvm_x86_msr_filter' to "msrs.h" too, if we put one 

  struct kvm_x86_msr_filter;

to <asm/kvm_host.h> before 'struct kvm_arch'.

The below diff passed build at my side:

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 1143140592df..f87b839fd3a4 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1291,13 +1291,6 @@ struct kvm_hv {
 };
 #endif
 
-struct msr_bitmap_range {
-       u32 flags;
-       u32 nmsrs;
-       u32 base;
-       unsigned long *bitmap;
-};
-
 #ifdef CONFIG_KVM_XEN
 /* Xen emulation context */
 struct kvm_xen {
@@ -1328,12 +1321,6 @@ enum kvm_suppress_eoi_broadcast_mode {
        KVM_SUPPRESS_EOI_BROADCAST_DISABLED /* Disable Suppress EOI broadcast */
 };
 
-struct kvm_x86_msr_filter {
-       u8 count;
-       bool default_allow:1;
-       struct msr_bitmap_range ranges[16];
-};
-
 struct kvm_x86_pmu_event_filter {
        __u32 action;
        __u32 nevents;
@@ -1478,6 +1465,8 @@ enum kvm_mmu_type {
        KVM_NR_MMU_TYPES,
 };
 
+struct kvm_x86_msr_filter;
+
 struct kvm_arch {
        unsigned long n_used_mmu_pages;
        unsigned long n_requested_mmu_pages;
diff --git a/arch/x86/kvm/msrs.h b/arch/x86/kvm/msrs.h
index 5c8362a8fd97..7a690a515947 100644
--- a/arch/x86/kvm/msrs.h
+++ b/arch/x86/kvm/msrs.h
@@ -13,6 +13,19 @@ extern bool ignore_msrs;
 
 extern u32 __read_mostly kvm_nr_uret_msrs;
 
+struct msr_bitmap_range {
+       u32 flags;
+       u32 nmsrs;
+       u32 base;
+       unsigned long *bitmap;
+};
+
+struct kvm_x86_msr_filter {
+       u8 count;
+       bool default_allow:1;
+       struct msr_bitmap_range ranges[16];
+};
+
 static inline void kvm_pr_unimpl_wrmsr(struct kvm_vcpu *vcpu, u32 msr, u64
data)
 {
        if (report_ignored_msrs)
@@ -153,4 +166,4 @@ static inline bool kvm_is_valid_u_s_cet(struct kvm_vcpu
*vcpu, u64 data)
        return true;
 }
 
-#endif
\ No newline at end of file
+#endif