KVM: VMX: replace move_msr_up with swap macro

PATCH In review Gustavo A. R. Silva 2 participants 3 messages Nov 3, 2017 – Nov 6, 2017

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Gustavo A. R. Silva

author

2017-11-03 22:58 UTC #0 lore raw

PATCH 1/1 KVM: VMX: replace move_msr_up with swap macro

Function move_msr_up is used to _manually_ swap MSR entries in MSR array. This function can be removed and replaced using the swap macro instead.

This code was detected with the help of Coccinelle.

Signed-off-by Gustavo A. R. Silva <[email protected]>

---
The new lines are over 80 characters, but I think in this case that is preferable over splitting them.

 arch/x86/kvm/vmx.c | 24 ++++++------------------
 1 file changed, 6 insertions(+), 18 deletions(-)

arch/x86/kvm/vmx.c +6 ~~-18~~

index e6c8ffa..210e491 100644
@@ -2544,18 +2544,6 @@ static bool vmx_invpcid_supported(void)
 	return cpu_has_vmx_invpcid() && enable_ept;
 }
 
-/*
- * Swap MSR entry in host/guest MSR entry array.
- */
-static void move_msr_up(struct vcpu_vmx *vmx, int from, int to)
-{
-	struct shared_msr_entry tmp;
-
-	tmp = vmx->guest_msrs[to];
-	vmx->guest_msrs[to] = vmx->guest_msrs[from];
-	vmx->guest_msrs[from] = tmp;
-}
-
 static void vmx_set_msr_bitmap(struct kvm_vcpu *vcpu)
 {
 	unsigned long *msr_bitmap;

@@ -2600,28 +2588,28 @@ static void setup_msrs(struct vcpu_vmx *vmx)
 	if (is_long_mode(&vmx->vcpu)) {
 		index = __find_msr_index(vmx, MSR_SYSCALL_MASK);
 		if (index >= 0)
-			move_msr_up(vmx, index, save_nmsrs++);
+			swap(vmx->guest_msrs[index], vmx->guest_msrs[save_nmsrs++]);
 		index = __find_msr_index(vmx, MSR_LSTAR);
 		if (index >= 0)
-			move_msr_up(vmx, index, save_nmsrs++);
+			swap(vmx->guest_msrs[index], vmx->guest_msrs[save_nmsrs++]);
 		index = __find_msr_index(vmx, MSR_CSTAR);
 		if (index >= 0)
-			move_msr_up(vmx, index, save_nmsrs++);
+			swap(vmx->guest_msrs[index], vmx->guest_msrs[save_nmsrs++]);
 		index = __find_msr_index(vmx, MSR_TSC_AUX);
 		if (index >= 0 && guest_cpuid_has(&vmx->vcpu, X86_FEATURE_RDTSCP))
-			move_msr_up(vmx, index, save_nmsrs++);
+			swap(vmx->guest_msrs[index], vmx->guest_msrs[save_nmsrs++]);
 		/*
 		 * MSR_STAR is only needed on long mode guests, and only
 		 * if efer.sce is enabled.
 		 */
 		index = __find_msr_index(vmx, MSR_STAR);
 		if ((index >= 0) && (vmx->vcpu.arch.efer & EFER_SCE))
-			move_msr_up(vmx, index, save_nmsrs++);
+			swap(vmx->guest_msrs[index], vmx->guest_msrs[save_nmsrs++]);
 	}
 #endif
 	index = __find_msr_index(vmx, MSR_EFER);
 	if (index >= 0 && update_transition_efer(vmx, index))
-		move_msr_up(vmx, index, save_nmsrs++);
+		swap(vmx->guest_msrs[index], vmx->guest_msrs[save_nmsrs++]);
 
 	vmx->save_nmsrs = save_nmsrs;

Signature · 1 line

2.7.4

Paolo Bonzini

maintainer

2017-11-04 17:29 UTC #1 lore raw

----- Original Message -----

Quoted 11 lines

From: "Gustavo A. R. Silva" <[email protected]>
To: "Paolo Bonzini" <[email protected]>, "Radim Krčmář" <[email protected]>, "Thomas Gleixner" <[email protected]>, "Ingo Molnar" <[email protected]>, "H. Peter Anvin" <[email protected]>, [email protected]
Cc: [email protected], [email protected], "Gustavo A. R. Silva" <[email protected]>
Sent: Friday, November 3, 2017 11:58:19 PM
Subject: [PATCH] KVM: VMX: replace move_msr_up with swap macro
Function move_msr_up is used to _manually_ swap MSR entries in MSR array. This function can be removed and replaced using the swap macro instead.
This code was detected with the help of Coccinelle.

I think move_msr_up should instead change into a function like

   void mark_msr_for_save(struct vcpu_vmx *vmx, int index)
   {
       swap(vmx->guest_msrs[index], vmx->guest_msrs[vmx->save_nmsrs]);
       vmx->save_nmsrs++;
   }

Using swap is useful, but it is also hiding what's going on exactly (in addition, using ++ inside a macro argument might be calling for trouble).

Paolo

Quoted 73 lines

Signed-off-by Gustavo A. R. Silva <[email protected]>

---
The new lines are over 80 characters, but I think in this case that is preferable over splitting them.

 arch/x86/kvm/vmx.c | 24 ++++++------------------
 1 file changed, 6 insertions(+), 18 deletions(-)

arch/x86/kvm/vmx.c +6 ~~-19~~

index e6c8ffa..210e491 100644
@@ -2544,18 +2544,6 @@ static bool vmx_invpcid_supported(void)
 	return cpu_has_vmx_invpcid() && enable_ept;
 }
 
-/*
- * Swap MSR entry in host/guest MSR entry array.
- */
-static void move_msr_up(struct vcpu_vmx *vmx, int from, int to)
-{
-	struct shared_msr_entry tmp;
-
-	tmp = vmx->guest_msrs[to];
-	vmx->guest_msrs[to] = vmx->guest_msrs[from];
-	vmx->guest_msrs[from] = tmp;
-}
-
 static void vmx_set_msr_bitmap(struct kvm_vcpu *vcpu)
 {
 	unsigned long *msr_bitmap;

@@ -2600,28 +2588,28 @@ static void setup_msrs(struct vcpu_vmx *vmx)
 	if (is_long_mode(&vmx->vcpu)) {
 		index = __find_msr_index(vmx, MSR_SYSCALL_MASK);
 		if (index >= 0)
-			move_msr_up(vmx, index, save_nmsrs++);
+			swap(vmx->guest_msrs[index], vmx->guest_msrs[save_nmsrs++]);
 		index = __find_msr_index(vmx, MSR_LSTAR);
 		if (index >= 0)
-			move_msr_up(vmx, index, save_nmsrs++);
+			swap(vmx->guest_msrs[index], vmx->guest_msrs[save_nmsrs++]);
 		index = __find_msr_index(vmx, MSR_CSTAR);
 		if (index >= 0)
-			move_msr_up(vmx, index, save_nmsrs++);
+			swap(vmx->guest_msrs[index], vmx->guest_msrs[save_nmsrs++]);
 		index = __find_msr_index(vmx, MSR_TSC_AUX);
 		if (index >= 0 && guest_cpuid_has(&vmx->vcpu, X86_FEATURE_RDTSCP))
-			move_msr_up(vmx, index, save_nmsrs++);
+			swap(vmx->guest_msrs[index], vmx->guest_msrs[save_nmsrs++]);
 		/*
 		 * MSR_STAR is only needed on long mode guests, and only
 		 * if efer.sce is enabled.
 		 */
 		index = __find_msr_index(vmx, MSR_STAR);
 		if ((index >= 0) && (vmx->vcpu.arch.efer & EFER_SCE))
-			move_msr_up(vmx, index, save_nmsrs++);
+			swap(vmx->guest_msrs[index], vmx->guest_msrs[save_nmsrs++]);
 	}
 #endif
 	index = __find_msr_index(vmx, MSR_EFER);
 	if (index >= 0 && update_transition_efer(vmx, index))
-		move_msr_up(vmx, index, save_nmsrs++);
+		swap(vmx->guest_msrs[index], vmx->guest_msrs[save_nmsrs++]);
 
 	vmx->save_nmsrs = save_nmsrs;
 
 
 
--

2.7.4

Gustavo A. R. Silva

author

2017-11-06 13:14 UTC #2 lore raw

Hi Paolo,

Quoting Paolo Bonzini <[email protected]>:

Quoted 21 lines

----- Original Message -----
Quoted 11 lines
From: "Gustavo A. R. Silva" <[email protected]>
To: "Paolo Bonzini" <[email protected]>, "Radim Krčmář" <[email protected]>, "Thomas Gleixner" <[email protected]>, "Ingo Molnar" <[email protected]>, "H. Peter Anvin" <[email protected]>, [email protected]
Cc: [email protected], [email protected], "Gustavo A. R. Silva" <[email protected]>
Sent: Friday, November 3, 2017 11:58:19 PM
Subject: [PATCH] KVM: VMX: replace move_msr_up with swap macro
Function move_msr_up is used to _manually_ swap MSR entries in MSR array. This function can be removed and replaced using the swap macro instead.
This code was detected with the help of Coccinelle.
I think move_msr_up should instead change into a function like
   void mark_msr_for_save(struct vcpu_vmx *vmx, int index)
   {
       swap(vmx->guest_msrs[index], vmx->guest_msrs[vmx->save_nmsrs]);
       vmx->save_nmsrs++;
   }

Quoted 4 lines

Using swap is useful, but it is also hiding what's going on exactly (in addition, using ++ inside a macro argument might be calling for trouble).

Thanks for your comments.

I'll work on v2 based on your feedback.

--
Gustavo A. R. Silva

Quoted 75 lines

Paolo

Quoted 73 lines

Signed-off-by Gustavo A. R. Silva <[email protected]>

---
The new lines are over 80 characters, but I think in this case that is preferable over splitting them.

 arch/x86/kvm/vmx.c | 24 ++++++------------------
 1 file changed, 6 insertions(+), 18 deletions(-)

arch/x86/kvm/vmx.c +6 ~~-19~~

index e6c8ffa..210e491 100644
@@ -2544,18 +2544,6 @@ static bool vmx_invpcid_supported(void)
 	return cpu_has_vmx_invpcid() && enable_ept;
 }
 
-/*
- * Swap MSR entry in host/guest MSR entry array.
- */
-static void move_msr_up(struct vcpu_vmx *vmx, int from, int to)
-{
-	struct shared_msr_entry tmp;
-
-	tmp = vmx->guest_msrs[to];
-	vmx->guest_msrs[to] = vmx->guest_msrs[from];
-	vmx->guest_msrs[from] = tmp;
-}
-
 static void vmx_set_msr_bitmap(struct kvm_vcpu *vcpu)
 {
 	unsigned long *msr_bitmap;

@@ -2600,28 +2588,28 @@ static void setup_msrs(struct vcpu_vmx *vmx)
 	if (is_long_mode(&vmx->vcpu)) {
 		index = __find_msr_index(vmx, MSR_SYSCALL_MASK);
 		if (index >= 0)
-			move_msr_up(vmx, index, save_nmsrs++);
+			swap(vmx->guest_msrs[index], vmx->guest_msrs[save_nmsrs++]);
 		index = __find_msr_index(vmx, MSR_LSTAR);
 		if (index >= 0)
-			move_msr_up(vmx, index, save_nmsrs++);
+			swap(vmx->guest_msrs[index], vmx->guest_msrs[save_nmsrs++]);
 		index = __find_msr_index(vmx, MSR_CSTAR);
 		if (index >= 0)
-			move_msr_up(vmx, index, save_nmsrs++);
+			swap(vmx->guest_msrs[index], vmx->guest_msrs[save_nmsrs++]);
 		index = __find_msr_index(vmx, MSR_TSC_AUX);
 		if (index >= 0 && guest_cpuid_has(&vmx->vcpu, X86_FEATURE_RDTSCP))
-			move_msr_up(vmx, index, save_nmsrs++);
+			swap(vmx->guest_msrs[index], vmx->guest_msrs[save_nmsrs++]);
 		/*
 		 * MSR_STAR is only needed on long mode guests, and only
 		 * if efer.sce is enabled.
 		 */
 		index = __find_msr_index(vmx, MSR_STAR);
 		if ((index >= 0) && (vmx->vcpu.arch.efer & EFER_SCE))
-			move_msr_up(vmx, index, save_nmsrs++);
+			swap(vmx->guest_msrs[index], vmx->guest_msrs[save_nmsrs++]);
 	}
 #endif
 	index = __find_msr_index(vmx, MSR_EFER);
 	if (index >= 0 && update_transition_efer(vmx, index))
-		move_msr_up(vmx, index, save_nmsrs++);
+		swap(vmx->guest_msrs[index], vmx->guest_msrs[save_nmsrs++]);
 
 	vmx->save_nmsrs = save_nmsrs;
 
 
 
--

2.7.4