linux-kernel - [PATCH 1/4] KVM: x86: hyperv: Remove duplicate definitions of Reference TSC Page

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Date:   Mon, 20 Apr 2020 10:38:35 -0700
From:   Michael Kelley <mikelley@...rosoft.com>
To:     kys@...rosoft.com, haiyangz@...rosoft.com, sthemmin@...rosoft.com,
        wei.liu@...nel.org, tglx@...utronix.de, mingo@...hat.com,
        bp@...en8.de, x86@...nel.org, hpa@...or.com, pbonzini@...hat.com,
        sean.j.christopherson@...el.com, vkuznets@...hat.com,
        wanpengli@...cent.com, jmattson@...gle.com, joro@...tes.org,
        kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-hyperv@...r.kernel.org
Cc:     mikelley@...rosoft.com
Subject: [PATCH 1/4] KVM: x86: hyperv: Remove duplicate definitions of Reference TSC Page

The Hyper-V Reference TSC Page structure is defined twice. struct
ms_hyperv_tsc_page has padding out to a full 4 Kbyte page size. But
the padding is not needed because the declaration includes a union
with HV_HYP_PAGE_SIZE.  KVM uses the second definition, which is
struct _HV_REFERENCE_TSC_PAGE, because it does not have the padding.

Fix the duplication by removing the padding from ms_hyperv_tsc_page.
Fix up the KVM code to use it. Remove the no longer used struct
_HV_REFERENCE_TSC_PAGE.

There is no functional change.

Signed-off-by: Michael Kelley <mikelley@...rosoft.com>
---
 arch/x86/include/asm/hyperv-tlfs.h | 8 --------
 arch/x86/include/asm/kvm_host.h    | 2 +-
 arch/x86/kvm/hyperv.c              | 4 ++--
 3 files changed, 3 insertions(+), 11 deletions(-)

diff --git a/arch/x86/include/asm/hyperv-tlfs.h b/arch/x86/include/asm/hyperv-tlfs.h
index 29336574d0bc..0e4d76920957 100644
--- a/arch/x86/include/asm/hyperv-tlfs.h
+++ b/arch/x86/include/asm/hyperv-tlfs.h
@@ -303,7 +303,6 @@ struct ms_hyperv_tsc_page {
 	u32 reserved1;
 	volatile u64 tsc_scale;
 	volatile s64 tsc_offset;
-	u64 reserved2[509];
 }  __packed;
 
 /*
@@ -433,13 +432,6 @@ enum HV_GENERIC_SET_FORMAT {
  */
 #define HV_CLOCK_HZ (NSEC_PER_SEC/100)
 
-typedef struct _HV_REFERENCE_TSC_PAGE {
-	__u32 tsc_sequence;
-	__u32 res1;
-	__u64 tsc_scale;
-	__s64 tsc_offset;
-}  __packed HV_REFERENCE_TSC_PAGE, *PHV_REFERENCE_TSC_PAGE;
-
 /* Define the number of synthetic interrupt sources. */
 #define HV_SYNIC_SINT_COUNT		(16)
 /* Define the expected SynIC version. */
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 42a2d0d3984a..4698343b9a05 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -865,7 +865,7 @@ struct kvm_hv {
 	u64 hv_crash_param[HV_X64_MSR_CRASH_PARAMS];
 	u64 hv_crash_ctl;
 
-	HV_REFERENCE_TSC_PAGE tsc_ref;
+	struct ms_hyperv_tsc_page tsc_ref;
 
 	struct idr conn_to_evt;
 
diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index bcefa9d4e57e..1f3c6fd3cdaa 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -900,7 +900,7 @@ static int kvm_hv_msr_set_crash_data(struct kvm_vcpu *vcpu,
  * These two equivalencies are implemented in this function.
  */
 static bool compute_tsc_page_parameters(struct pvclock_vcpu_time_info *hv_clock,
-					HV_REFERENCE_TSC_PAGE *tsc_ref)
+					struct ms_hyperv_tsc_page *tsc_ref)
 {
 	u64 max_mul;
 
@@ -941,7 +941,7 @@ void kvm_hv_setup_tsc_page(struct kvm *kvm,
 	u64 gfn;
 
 	BUILD_BUG_ON(sizeof(tsc_seq) != sizeof(hv->tsc_ref.tsc_sequence));
-	BUILD_BUG_ON(offsetof(HV_REFERENCE_TSC_PAGE, tsc_sequence) != 0);
+	BUILD_BUG_ON(offsetof(struct ms_hyperv_tsc_page, tsc_sequence) != 0);
 
 	if (!(hv->hv_tsc_page & HV_X64_MSR_TSC_REFERENCE_ENABLE))
 		return;
-- 
2.18.2