[PATCH v11 03/46] KVM: SVM: Add a proper field for Hyper-V VMCB enlightenments

Vitaly Kuznetsov
2022-10-04T12:40:34Z

From: Sean Christopherson <seanjc@google.com>

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>
---
arch/x86/include/asm/svm.h | 7 ++++++-
arch/x86/kvm/svm/nested.c | 9 ++++-----
arch/x86/kvm/svm/svm.h | 5 ++++-
arch/x86/kvm/svm/svm_onhyperv.c | 2 +-
arch/x86/kvm/svm/svm_onhyperv.h | 15 +++++++--------
tools/testing/selftests/kvm/include/x86_64/svm.h | 5 ++++-
.../selftests/kvm/x86_64/hyperv_svm_test.c | 3 +--
7 files changed, 27 insertions(+), 19 deletions(-)

diff --git a/arch/x86/include/asm/svm.h b/arch/x86/include/asm/svm.h
index 0361626841bc..6befed2b30a6 100644
--- 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 3131c4476b7b..c8e967f6cafe 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -179,8 +179,7 @@ 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;

/*
@@ -369,8 +368,8 @@ 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));
}
}

@@ -1479,7 +1478,7 @@ 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 6a7686bf6900..9eb2fc76732f 100644
--- 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 ed5e79392544..422d00fee24a 100644
--- 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 66e61a73caeb..5c664dd7bee2 100644
--- 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 89ce2c6b57fe..6e1527aa3419 100644
--- 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 2fd64b419928..8ef6a4c83cb1 100644
--- 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);

--
2.37.3