[PATCH 2/2] kvm/x86: use __test_bit

[Michael S. Tsirkin]

Let compiler do slightly better optimizations using
the non-volatile __test_bit in all cases where
the values are set using the non-volatile __set_bit and
__clear_bit.

I left test_bit in place where the mask is set  using
the atomic set_bit/clear_bit, for symmetry.

This shaves about 100 bytes off the kernel size:

before:
134868         2997    8372  146237   23b3d arch/x86/kvm/kvm-intel.ko
343129        47640     441  391210   5f82a arch/x86/kvm/kvm.ko
after:
134836          2997    8372  146205   23b1d arch/x86/kvm/kvm-intel.ko
343017         47640     441  391098   5f7ba arch/x86/kvm/kvm.ko

Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
---
 arch/x86/kvm/ioapic.h         |  2 +-
 arch/x86/kvm/kvm_cache_regs.h |  6 +++---
 arch/x86/kvm/ioapic.c         |  2 +-
 arch/x86/kvm/pmu_intel.c      |  2 +-
 arch/x86/kvm/vmx.c            | 18 +++++++++---------
 arch/x86/kvm/x86.c            |  2 +-
 6 files changed, 16 insertions(+), 16 deletions(-)

diff --git a/arch/x86/kvm/ioapic.h b/arch/x86/kvm/ioapic.h
index ca0b0b4..3b58d41 100644
--- a/arch/x86/kvm/ioapic.h
+++ b/arch/x86/kvm/ioapic.h
@@ -102,7 +102,7 @@ static inline bool kvm_ioapic_handles_vector(struct kvm *kvm, int vector)
 {
 	struct kvm_ioapic *ioapic = kvm->arch.vioapic;
 	smp_rmb();
-	return test_bit(vector, ioapic->handled_vectors);
+	return __test_bit(vector, ioapic->handled_vectors);
 }
 
 void kvm_rtc_eoi_tracking_restore_one(struct kvm_vcpu *vcpu);
diff --git a/arch/x86/kvm/kvm_cache_regs.h b/arch/x86/kvm/kvm_cache_regs.h
index e1e89ee..21ef6d6 100644
--- a/arch/x86/kvm/kvm_cache_regs.h
+++ b/arch/x86/kvm/kvm_cache_regs.h
@@ -9,7 +9,7 @@
 static inline unsigned long kvm_register_read(struct kvm_vcpu *vcpu,
 					      enum kvm_reg reg)
 {
-	if (!test_bit(reg, (unsigned long *)&vcpu->arch.regs_avail))
+	if (!__test_bit(reg, (unsigned long *)&vcpu->arch.regs_avail))
 		kvm_x86_ops->cache_reg(vcpu, reg);
 
 	return vcpu->arch.regs[reg];
@@ -38,7 +38,7 @@ static inline u64 kvm_pdptr_read(struct kvm_vcpu *vcpu, int index)
 {
 	might_sleep();  /* on svm */
 
-	if (!test_bit(VCPU_EXREG_PDPTR,
+	if (!__test_bit(VCPU_EXREG_PDPTR,
 		      (unsigned long *)&vcpu->arch.regs_avail))
 		kvm_x86_ops->cache_reg(vcpu, VCPU_EXREG_PDPTR);
 
@@ -68,7 +68,7 @@ static inline ulong kvm_read_cr4_bits(struct kvm_vcpu *vcpu, ulong mask)
 
 static inline ulong kvm_read_cr3(struct kvm_vcpu *vcpu)
 {
-	if (!test_bit(VCPU_EXREG_CR3, (ulong *)&vcpu->arch.regs_avail))
+	if (!__test_bit(VCPU_EXREG_CR3, (ulong *)&vcpu->arch.regs_avail))
 		kvm_x86_ops->decache_cr3(vcpu);
 	return vcpu->arch.cr3;
 }
diff --git a/arch/x86/kvm/ioapic.c b/arch/x86/kvm/ioapic.c
index 856f791..bf2afa5 100644
--- a/arch/x86/kvm/ioapic.c
+++ b/arch/x86/kvm/ioapic.c
@@ -117,7 +117,7 @@ static void __rtc_irq_eoi_tracking_restore_one(struct kvm_vcpu *vcpu)
 		return;
 
 	new_val = kvm_apic_pending_eoi(vcpu, e->fields.vector);
-	old_val = test_bit(vcpu->vcpu_id, ioapic->rtc_status.dest_map);
+	old_val = __test_bit(vcpu->vcpu_id, ioapic->rtc_status.dest_map);
 
 	if (new_val == old_val)
 		return;
diff --git a/arch/x86/kvm/pmu_intel.c b/arch/x86/kvm/pmu_intel.c
index ab38af4..fb20a0f 100644
--- a/arch/x86/kvm/pmu_intel.c
+++ b/arch/x86/kvm/pmu_intel.c
@@ -98,7 +98,7 @@ static bool intel_pmc_is_enabled(struct kvm_pmc *pmc)
 {
 	struct kvm_pmu *pmu = pmc_to_pmu(pmc);
 
-	return test_bit(pmc->idx, (unsigned long *)&pmu->global_ctrl);
+	return __test_bit(pmc->idx, (unsigned long *)&pmu->global_ctrl);
 }
 
 static struct kvm_pmc *intel_pmc_idx_to_pmc(struct kvm_pmu *pmu, int pmc_idx)
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index c117703..ed44026 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -2025,7 +2025,7 @@ static unsigned long vmx_get_rflags(struct kvm_vcpu *vcpu)
 {
 	unsigned long rflags, save_rflags;
 
-	if (!test_bit(VCPU_EXREG_RFLAGS, (ulong *)&vcpu->arch.regs_avail)) {
+	if (!__test_bit(VCPU_EXREG_RFLAGS, (ulong *)&vcpu->arch.regs_avail)) {
 		__set_bit(VCPU_EXREG_RFLAGS, (ulong *)&vcpu->arch.regs_avail);
 		rflags = vmcs_readl(GUEST_RFLAGS);
 		if (to_vmx(vcpu)->rmode.vm86_active) {
@@ -3478,7 +3478,7 @@ static void ept_load_pdptrs(struct kvm_vcpu *vcpu)
 {
 	struct kvm_mmu *mmu = vcpu->arch.walk_mmu;
 
-	if (!test_bit(VCPU_EXREG_PDPTR,
+	if (!__test_bit(VCPU_EXREG_PDPTR,
 		      (unsigned long *)&vcpu->arch.regs_dirty))
 		return;
 
@@ -3513,7 +3513,7 @@ static void ept_update_paging_mode_cr0(unsigned long *hw_cr0,
 					unsigned long cr0,
 					struct kvm_vcpu *vcpu)
 {
-	if (!test_bit(VCPU_EXREG_CR3, (ulong *)&vcpu->arch.regs_avail))
+	if (!__test_bit(VCPU_EXREG_CR3, (ulong *)&vcpu->arch.regs_avail))
 		vmx_decache_cr3(vcpu);
 	if (!(cr0 & X86_CR0_PG)) {
 		/* From paging/starting to nonpaging */
@@ -4275,24 +4275,24 @@ static void nested_vmx_disable_intercept_for_msr(unsigned long *msr_bitmap_l1,
 	 */
 	if (msr <= 0x1fff) {
 		if (type & MSR_TYPE_R &&
-		   !test_bit(msr, msr_bitmap_l1 + 0x000 / f))
+		   !__test_bit(msr, msr_bitmap_l1 + 0x000 / f))
 			/* read-low */
 			__clear_bit(msr, msr_bitmap_nested + 0x000 / f);
 
 		if (type & MSR_TYPE_W &&
-		   !test_bit(msr, msr_bitmap_l1 + 0x800 / f))
+		   !__test_bit(msr, msr_bitmap_l1 + 0x800 / f))
 			/* write-low */
 			__clear_bit(msr, msr_bitmap_nested + 0x800 / f);
 
 	} else if ((msr >= 0xc0000000) && (msr <= 0xc0001fff)) {
 		msr &= 0x1fff;
 		if (type & MSR_TYPE_R &&
-		   !test_bit(msr, msr_bitmap_l1 + 0x400 / f))
+		   !__test_bit(msr, msr_bitmap_l1 + 0x400 / f))
 			/* read-high */
 			__clear_bit(msr, msr_bitmap_nested + 0x400 / f);
 
 		if (type & MSR_TYPE_W &&
-		   !test_bit(msr, msr_bitmap_l1 + 0xc00 / f))
+		   !__test_bit(msr, msr_bitmap_l1 + 0xc00 / f))
 			/* write-high */
 			__clear_bit(msr, msr_bitmap_nested + 0xc00 / f);
 
@@ -8316,9 +8316,9 @@ static void __noclone vmx_vcpu_run(struct kvm_vcpu *vcpu)
 		vmx->nested.sync_shadow_vmcs = false;
 	}
 
-	if (test_bit(VCPU_REGS_RSP, (unsigned long *)&vcpu->arch.regs_dirty))
+	if (__test_bit(VCPU_REGS_RSP, (unsigned long *)&vcpu->arch.regs_dirty))
 		vmcs_writel(GUEST_RSP, vcpu->arch.regs[VCPU_REGS_RSP]);
-	if (test_bit(VCPU_REGS_RIP, (unsigned long *)&vcpu->arch.regs_dirty))
+	if (__test_bit(VCPU_REGS_RIP, (unsigned long *)&vcpu->arch.regs_dirty))
 		vmcs_writel(GUEST_RIP, vcpu->arch.regs[VCPU_REGS_RIP]);
 
 	cr4 = cr4_read_shadow();
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 5ef2560..c8015fa 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -555,7 +555,7 @@ static bool pdptrs_changed(struct kvm_vcpu *vcpu)
 	if (is_long_mode(vcpu) || !is_pae(vcpu))
 		return false;
 
-	if (!test_bit(VCPU_EXREG_PDPTR,
+	if (!__test_bit(VCPU_EXREG_PDPTR,
 		      (unsigned long *)&vcpu->arch.regs_avail))
 		return true;
 
-- 
MST

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