Commit f98c1e77 authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
Browse files

KVM: VMX: Add proper cache tracking for CR4 



Move CR4 caching into the standard register caching mechanism in order
to take advantage of the availability checks provided by regs_avail.
This avoids multiple VMREADs and retpolines (when configured) during
nested VMX transitions as kvm_read_cr4_bits() is invoked multiple times
on each transition, e.g. when stuffing CR0 and CR3.

As an added bonus, this eliminates a kvm_x86_ops hook, saves a retpoline
on SVM when reading CR4, and squashes the confusing naming discrepancy
of "cache_reg" vs. "decache_cr4_guest_bits".

No functional change intended.

Signed-off-by: default avatarSean Christopherson <sean.j.christopherson@intel.com>
Message-Id: <20200502043234.12481-7-sean.j.christopherson@intel.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 0cc69204

arch/x86/include/asm/kvm_host.h

+1 −1
Original line number Diff line number Diff line
@@ -168,6 +168,7 @@ enum kvm_reg { 


	VCPU_EXREG_PDPTR = NR_VCPU_REGS,

	VCPU_EXREG_CR3,

	VCPU_EXREG_CR4,

	VCPU_EXREG_RFLAGS,

	VCPU_EXREG_SEGMENTS,

	VCPU_EXREG_EXIT_INFO_1,
@@ -1092,7 +1093,6 @@ struct kvm_x86_ops { 
			    struct kvm_segment *var, int seg);

	void (*get_cs_db_l_bits)(struct kvm_vcpu *vcpu, int *db, int *l);

	void (*decache_cr0_guest_bits)(struct kvm_vcpu *vcpu);

	void (*decache_cr4_guest_bits)(struct kvm_vcpu *vcpu);

	void (*set_cr0)(struct kvm_vcpu *vcpu, unsigned long cr0);

	int (*set_cr4)(struct kvm_vcpu *vcpu, unsigned long cr4);

	void (*set_efer)(struct kvm_vcpu *vcpu, u64 efer);

arch/x86/kvm/kvm_cache_regs.h

+3 −2
Original line number Diff line number Diff line
@@ -129,8 +129,9 @@ static inline ulong kvm_read_cr0(struct kvm_vcpu *vcpu) 
static inline ulong kvm_read_cr4_bits(struct kvm_vcpu *vcpu, ulong mask)

{

	ulong tmask = mask & KVM_POSSIBLE_CR4_GUEST_BITS;

	if (tmask & vcpu->arch.cr4_guest_owned_bits)

		kvm_x86_ops.decache_cr4_guest_bits(vcpu);

	if ((tmask & vcpu->arch.cr4_guest_owned_bits) &&

	    !kvm_register_is_available(vcpu, VCPU_EXREG_CR4))

		kvm_x86_ops.cache_reg(vcpu, VCPU_EXREG_CR4);

	return vcpu->arch.cr4 & mask;

}

arch/x86/kvm/svm/svm.c

+0 −5
Original line number Diff line number Diff line
@@ -1525,10 +1525,6 @@ static void svm_decache_cr0_guest_bits(struct kvm_vcpu *vcpu) 
{

}



static void svm_decache_cr4_guest_bits(struct kvm_vcpu *vcpu)

{

}



static void update_cr0_intercept(struct vcpu_svm *svm)

{

	ulong gcr0 = svm->vcpu.arch.cr0;
@@ -4007,7 +4003,6 @@ static struct kvm_x86_ops svm_x86_ops __initdata = { 
	.get_cpl = svm_get_cpl,

	.get_cs_db_l_bits = kvm_get_cs_db_l_bits,

	.decache_cr0_guest_bits = svm_decache_cr0_guest_bits,

	.decache_cr4_guest_bits = svm_decache_cr4_guest_bits,

	.set_cr0 = svm_set_cr0,

	.set_cr4 = svm_set_cr4,

	.set_efer = svm_set_efer,

arch/x86/kvm/vmx/vmx.c

+9 −9
Original line number Diff line number Diff line
@@ -2204,6 +2204,8 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) 


static void vmx_cache_reg(struct kvm_vcpu *vcpu, enum kvm_reg reg)

{

	unsigned long guest_owned_bits;



	kvm_register_mark_available(vcpu, reg);



	switch (reg) {
@@ -2221,6 +2223,12 @@ static void vmx_cache_reg(struct kvm_vcpu *vcpu, enum kvm_reg reg) 
		if (enable_unrestricted_guest || (enable_ept && is_paging(vcpu)))

			vcpu->arch.cr3 = vmcs_readl(GUEST_CR3);

		break;

	case VCPU_EXREG_CR4:

		guest_owned_bits = vcpu->arch.cr4_guest_owned_bits;



		vcpu->arch.cr4 &= ~guest_owned_bits;

		vcpu->arch.cr4 |= vmcs_readl(GUEST_CR4) & guest_owned_bits;

		break;

	default:

		WARN_ON_ONCE(1);

		break;
@@ -2922,14 +2930,6 @@ static void vmx_decache_cr0_guest_bits(struct kvm_vcpu *vcpu) 
	vcpu->arch.cr0 |= vmcs_readl(GUEST_CR0) & cr0_guest_owned_bits;

}



static void vmx_decache_cr4_guest_bits(struct kvm_vcpu *vcpu)

{

	ulong cr4_guest_owned_bits = vcpu->arch.cr4_guest_owned_bits;



	vcpu->arch.cr4 &= ~cr4_guest_owned_bits;

	vcpu->arch.cr4 |= vmcs_readl(GUEST_CR4) & cr4_guest_owned_bits;

}



static void ept_load_pdptrs(struct kvm_vcpu *vcpu)

{

	struct kvm_mmu *mmu = vcpu->arch.walk_mmu;
@@ -3128,6 +3128,7 @@ int vmx_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4) 
		return 1;



	vcpu->arch.cr4 = cr4;

	kvm_register_mark_available(vcpu, VCPU_EXREG_CR4);



	if (!enable_unrestricted_guest) {

		if (enable_ept) {
@@ -7809,7 +7810,6 @@ static struct kvm_x86_ops vmx_x86_ops __initdata = { 
	.get_cpl = vmx_get_cpl,

	.get_cs_db_l_bits = vmx_get_cs_db_l_bits,

	.decache_cr0_guest_bits = vmx_decache_cr0_guest_bits,

	.decache_cr4_guest_bits = vmx_decache_cr4_guest_bits,

	.set_cr0 = vmx_set_cr0,

	.set_cr4 = vmx_set_cr4,

	.set_efer = vmx_set_efer,

arch/x86/kvm/vmx/vmx.h

+1 −0
Original line number Diff line number Diff line
@@ -453,6 +453,7 @@ static inline void vmx_register_cache_reset(struct kvm_vcpu *vcpu) 
				  | (1 << VCPU_EXREG_PDPTR)

				  | (1 << VCPU_EXREG_SEGMENTS)

				  | (1 << VCPU_EXREG_CR3)

				  | (1 << VCPU_EXREG_CR4)

				  | (1 << VCPU_EXREG_EXIT_INFO_1)

				  | (1 << VCPU_EXREG_EXIT_INFO_2));

	vcpu->arch.regs_dirty = 0;

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