[PATCH v1 4/6] KVM: VMX: Allocate XSAVE area for Intel PT configuration

[Luwei Kang]

Allocate XSAVE area for host and guest Intel PT
configuration when Intel PT working in HOST_GUEST
mode. Intel PT configuration state can be saved
using XSAVES and restored by XRSTORS instruction.

Signed-off-by: Luwei Kang <luwei.kang@xxxxxxxxx>
---
 arch/x86/kvm/vmx/vmx.c | 25 ++++++++++++++++++++++++-
 arch/x86/kvm/vmx/vmx.h |  3 +++
 2 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 4595230..4691665 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -1033,6 +1033,7 @@ static void pt_guest_exit(struct vcpu_vmx *vmx)
 
 static int pt_init(struct vcpu_vmx *vmx)
 {
+	unsigned int eax, ebx, ecx, edx;
 	u32 pt_state_sz = sizeof(struct pt_state) + sizeof(u64) *
 		intel_pt_validate_hw_cap(PT_CAP_num_address_ranges) * 2;
 
@@ -1044,13 +1045,35 @@ static int pt_init(struct vcpu_vmx *vmx)
 	vmx->pt_desc->host_ctx = (struct pt_state *)(vmx->pt_desc + 1);
 	vmx->pt_desc->guest_ctx = (void *)vmx->pt_desc->host_ctx + pt_state_sz;
 
+	cpuid_count(XSTATE_CPUID, 1, &eax, &ebx, &ecx, &edx);
+	if (ecx & XFEATURE_MASK_PT) {
+		vmx->pt_desc->host_xs = kmem_cache_zalloc(x86_fpu_cache,
+							GFP_KERNEL_ACCOUNT);
+		vmx->pt_desc->guest_xs = kmem_cache_zalloc(x86_fpu_cache,
+							GFP_KERNEL_ACCOUNT);
+		if (!vmx->pt_desc->host_xs || !vmx->pt_desc->guest_xs) {
+			if (vmx->pt_desc->host_xs)
+				kmem_cache_free(x86_fpu_cache,
+						vmx->pt_desc->host_xs);
+			if (vmx->pt_desc->guest_xs)
+				kmem_cache_free(x86_fpu_cache,
+						vmx->pt_desc->guest_xs);
+		} else
+			vmx->pt_desc->pt_xsave = true;
+	}
+
 	return 0;
 }
 
 static void pt_uninit(struct vcpu_vmx *vmx)
 {
-	if (pt_mode == PT_MODE_HOST_GUEST)
+	if (pt_mode == PT_MODE_HOST_GUEST) {
 		kfree(vmx->pt_desc);
+		if (vmx->pt_desc->pt_xsave) {
+			kmem_cache_free(x86_fpu_cache, vmx->pt_desc->host_xs);
+			kmem_cache_free(x86_fpu_cache, vmx->pt_desc->guest_xs);
+		}
+	}
 }
 
 void vmx_prepare_switch_to_guest(struct kvm_vcpu *vcpu)
diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
index 283f69d..e103991 100644
--- a/arch/x86/kvm/vmx/vmx.h
+++ b/arch/x86/kvm/vmx/vmx.h
@@ -69,8 +69,11 @@ struct pt_desc {
 	u64 ctl_bitmask;
 	u32 addr_range;
 	u32 caps[PT_CPUID_REGS_NUM * PT_CPUID_LEAVES];
+	bool pt_xsave;
 	struct pt_state *host_ctx;
 	struct pt_state *guest_ctx;
+	struct fpu *host_xs;
+	struct fpu *guest_xs;
 };
 
 /*
-- 
1.8.3.1