KVM: SVM: Add a proper field for Hyper-V VMCB enlightenments

Add a union to provide hv_enlightenments side-by-side with the sw_reserved
bytes that Hyper-V's enlightenments overlay.  Casting sw_reserved
everywhere is messy, confusing, and unnecessarily unsafe.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20221101145426.251680-4-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/include/asm/svm.h b/arch/x86/include/asm/svm.h
index 4352b46..b37249e 100644 (file)
--- a/arch/x86/include/asm/svm.h
+++ b/arch/x86/include/asm/svm.h
@@ -5,6 +5,8 @@
 #include <uapi/asm/svm.h>
 #include <uapi/asm/kvm.h>
 
+#include <asm/hyperv-tlfs.h>
+
 /*
  * 32-bit intercept words in the VMCB Control Area, starting
  * at Byte offset 000h.
@@ -161,7 +163,10 @@ struct __attribute__ ((__packed__)) vmcb_control_area {
         * Offset 0x3e0, 32 bytes reserved
         * for use by hypervisor/software.
         */
-       u8 reserved_sw[32];
+       union {
+               struct hv_enlightenments hv_enlightenments;
+               u8 reserved_sw[32];
+       };
 };
 
 

diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index a2f25bf..622fe00 100644 (file)
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -180,8 +180,7 @@ void recalc_intercepts(struct vcpu_svm *svm)
  */
 static bool nested_svm_vmrun_msrpm(struct vcpu_svm *svm)
 {
-       struct hv_enlightenments *hve =
-               (struct hv_enlightenments *)svm->nested.ctl.reserved_sw;
+       struct hv_enlightenments *hve = &svm->nested.ctl.hv_enlightenments;
        int i;
 
        /*
@@ -370,8 +369,8 @@ void __nested_copy_vmcb_control_to_cache(struct kvm_vcpu *vcpu,
        /* Hyper-V extensions (Enlightened VMCB) */
        if (kvm_hv_hypercall_enabled(vcpu)) {
                to->clean = from->clean;
-               memcpy(to->reserved_sw, from->reserved_sw,
-                      sizeof(struct hv_enlightenments));
+               memcpy(&to->hv_enlightenments, &from->hv_enlightenments,
+                      sizeof(to->hv_enlightenments));
        }
 }
 
@@ -1488,7 +1487,7 @@ static void nested_copy_vmcb_cache_to_control(struct vmcb_control_area *dst,
        dst->virt_ext              = from->virt_ext;
        dst->pause_filter_count   = from->pause_filter_count;
        dst->pause_filter_thresh  = from->pause_filter_thresh;
-       /* 'clean' and 'reserved_sw' are not changed by KVM */
+       /* 'clean' and 'hv_enlightenments' are not changed by KVM */
 }
 
 static int svm_get_nested_state(struct kvm_vcpu *vcpu,

diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index 199a2ec..a5af367 100644 (file)
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -151,7 +151,10 @@ struct vmcb_ctrl_area_cached {
        u64 nested_cr3;
        u64 virt_ext;
        u32 clean;
-       u8 reserved_sw[32];
+       union {
+               struct hv_enlightenments hv_enlightenments;
+               u8 reserved_sw[32];
+       };
 };
 
 struct svm_nested_state {

diff --git a/arch/x86/kvm/svm/svm_onhyperv.c b/arch/x86/kvm/svm/svm_onhyperv.c
index ed5e793..422d00f 100644 (file)
--- a/arch/x86/kvm/svm/svm_onhyperv.c
+++ b/arch/x86/kvm/svm/svm_onhyperv.c
@@ -26,7 +26,7 @@ int svm_hv_enable_direct_tlbflush(struct kvm_vcpu *vcpu)
        if (!*p_hv_pa_pg)
                return -ENOMEM;
 
-       hve = (struct hv_enlightenments *)to_svm(vcpu)->vmcb->control.reserved_sw;
+       hve = &to_svm(vcpu)->vmcb->control.hv_enlightenments;
 
        hve->partition_assist_page = __pa(*p_hv_pa_pg);
        hve->hv_vm_id = (unsigned long)vcpu->kvm;

diff --git a/arch/x86/kvm/svm/svm_onhyperv.h b/arch/x86/kvm/svm/svm_onhyperv.h
index 66e61a7..5c664dd 100644 (file)
--- a/arch/x86/kvm/svm/svm_onhyperv.h
+++ b/arch/x86/kvm/svm/svm_onhyperv.h
@@ -17,8 +17,10 @@ int svm_hv_enable_direct_tlbflush(struct kvm_vcpu *vcpu);
 
 static inline void svm_hv_init_vmcb(struct vmcb *vmcb)
 {
-       struct hv_enlightenments *hve =
-               (struct hv_enlightenments *)vmcb->control.reserved_sw;
+       struct hv_enlightenments *hve = &vmcb->control.hv_enlightenments;
+
+       BUILD_BUG_ON(sizeof(vmcb->control.hv_enlightenments) !=
+                    sizeof(vmcb->control.reserved_sw));
 
        if (npt_enabled &&
            ms_hyperv.nested_features & HV_X64_NESTED_ENLIGHTENED_TLB)
@@ -60,18 +62,15 @@ static inline void svm_hv_vmcb_dirty_nested_enlightenments(
                struct kvm_vcpu *vcpu)
 {
        struct vmcb *vmcb = to_svm(vcpu)->vmcb;
-       struct hv_enlightenments *hve =
-               (struct hv_enlightenments *)vmcb->control.reserved_sw;
+       struct hv_enlightenments *hve = &vmcb->control.hv_enlightenments;
 
        if (hve->hv_enlightenments_control.msr_bitmap)
                vmcb_mark_dirty(vmcb, HV_VMCB_NESTED_ENLIGHTENMENTS);
 }
 
-static inline void svm_hv_update_vp_id(struct vmcb *vmcb,
-               struct kvm_vcpu *vcpu)
+static inline void svm_hv_update_vp_id(struct vmcb *vmcb, struct kvm_vcpu *vcpu)
 {
-       struct hv_enlightenments *hve =
-               (struct hv_enlightenments *)vmcb->control.reserved_sw;
+       struct hv_enlightenments *hve = &vmcb->control.hv_enlightenments;
        u32 vp_index = kvm_hv_get_vpindex(vcpu);
 
        if (hve->hv_vp_id != vp_index) {

diff --git a/tools/testing/selftests/kvm/include/x86_64/svm.h b/tools/testing/selftests/kvm/include/x86_64/svm.h
index 89ce2c6..6e1527a 100644 (file)
--- a/tools/testing/selftests/kvm/include/x86_64/svm.h
+++ b/tools/testing/selftests/kvm/include/x86_64/svm.h
@@ -123,7 +123,10 @@ struct __attribute__ ((__packed__)) vmcb_control_area {
         * Offset 0x3e0, 32 bytes reserved
         * for use by hypervisor/software.
         */
-       u8 reserved_sw[32];
+       union {
+               struct hv_enlightenments hv_enlightenments;
+               u8 reserved_sw[32];
+       };
 };
 
 

diff --git a/tools/testing/selftests/kvm/x86_64/hyperv_svm_test.c b/tools/testing/selftests/kvm/x86_64/hyperv_svm_test.c
index 2fd64b4..8ef6a4c 100644 (file)
--- a/tools/testing/selftests/kvm/x86_64/hyperv_svm_test.c
+++ b/tools/testing/selftests/kvm/x86_64/hyperv_svm_test.c
@@ -46,8 +46,7 @@ static void __attribute__((__flatten__)) guest_code(struct svm_test_data *svm)
 {
        unsigned long l2_guest_stack[L2_GUEST_STACK_SIZE];
        struct vmcb *vmcb = svm->vmcb;
-       struct hv_enlightenments *hve =
-               (struct hv_enlightenments *)vmcb->control.reserved_sw;
+       struct hv_enlightenments *hve = &vmcb->control.hv_enlightenments;
 
        GUEST_SYNC(1);