KVM: SVM: Implement LBR virtualization

KVM: SVM: Implement LBR virtualization

[Joerg Roedel]

This patch set enables the virtualization of the last branch record in SVM if
this feature is supported by the hardware. To the previous post the fix for the
XP 64 bit install crash has been removed from this series and was posted
seperatly to keep it small enough for 2.6.25. This patch set applies on top of
that fix.

Joerg

diffstat:

 arch/x86/kvm/kvm_svm.h |    2 +
 arch/x86/kvm/svm.c     |  118 ++++++++++++++++++++++++++++++-----------------
 2 files changed, 77 insertions(+), 43 deletions(-)





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[PATCH 1/3] KVM: SVM: let init_vmcb() take struct vcpu_svm as parameter

[Joerg Roedel]

Change the parameter of the init_vmcb() function in the kvm-amd module from
struct vmcb to struct vcpu_svm.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Markus Rechberger <markus.rechberger@amd.com>
---
 arch/x86/kvm/svm.c |   12 ++++++------
 1 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 1ef3e7b..5a69619 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -471,10 +471,10 @@ static void init_sys_seg(struct vmcb_seg *seg, uint32_t type)
 	seg->base = 0;
 }
 
-static void init_vmcb(struct vmcb *vmcb)
+static void init_vmcb(struct vcpu_svm *svm)
 {
-	struct vmcb_control_area *control = &vmcb->control;
-	struct vmcb_save_area *save = &vmcb->save;
+	struct vmcb_control_area *control = &svm->vmcb->control;
+	struct vmcb_save_area *save = &svm->vmcb->save;
 
 	control->intercept_cr_read = 	INTERCEPT_CR0_MASK |
 					INTERCEPT_CR3_MASK |
@@ -600,7 +600,7 @@ static int svm_vcpu_reset(struct kvm_vcpu *vcpu)
 {
 	struct vcpu_svm *svm = to_svm(vcpu);
 
-	init_vmcb(svm->vmcb);
+	init_vmcb(svm);
 
 	if (vcpu->vcpu_id != 0) {
 		svm->vmcb->save.rip = 0;
@@ -638,7 +638,7 @@ static struct kvm_vcpu *svm_create_vcpu(struct kvm *kvm, unsigned int id)
 	svm->vmcb_pa = page_to_pfn(page) << PAGE_SHIFT;
 	svm->asid_generation = 0;
 	memset(svm->db_regs, 0, sizeof(svm->db_regs));
-	init_vmcb(svm->vmcb);
+	init_vmcb(svm);
 
 	fx_init(&svm->vcpu);
 	svm->vcpu.fpu_active = 1;
@@ -1024,7 +1024,7 @@ static int shutdown_interception(struct vcpu_svm *svm, struct kvm_run *kvm_run)
 	 * so reinitialize it.
 	 */
 	clear_page(svm->vmcb);
-	init_vmcb(svm->vmcb);
+	init_vmcb(svm);
 
 	kvm_run->exit_reason = KVM_EXIT_SHUTDOWN;
 	return 0;
-- 
1.5.3.7




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[PATCH 2/3] KVM: SVM: allocate the MSR permission map per VCPU

[Joerg Roedel]

This patch changes the kvm-amd module to allocate the SVM MSR permission map
per VCPU instead of a global map for all VCPUs. With this we have more
flexibility allowing specific guests to access virtualized MSRs. This is
required for LBR virtualization.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Markus Rechberger <markus.rechberger@amd.com>
---
 arch/x86/kvm/kvm_svm.h |    2 +
 arch/x86/kvm/svm.c     |   67 +++++++++++++++++++++++-------------------------
 2 files changed, 34 insertions(+), 35 deletions(-)

diff --git a/arch/x86/kvm/kvm_svm.h b/arch/x86/kvm/kvm_svm.h
index ecdfe97..65ef0fc 100644
--- a/arch/x86/kvm/kvm_svm.h
+++ b/arch/x86/kvm/kvm_svm.h
@@ -39,6 +39,8 @@ struct vcpu_svm {
 	unsigned long host_db_regs[NUM_DB_REGS];
 	unsigned long host_dr6;
 	unsigned long host_dr7;
+
+	u32 *msrpm;
 };
 
 #endif
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 5a69619..3b31162 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -65,7 +65,6 @@ static inline struct vcpu_svm *to_svm(struct kvm_vcpu *vcpu)
 }
 
 unsigned long iopm_base;
-unsigned long msrpm_base;
 
 struct kvm_ldttss_desc {
 	u16 limit0;
@@ -370,12 +369,29 @@ static void set_msr_interception(u32 *msrpm, unsigned msr,
 	BUG();
 }
 
+static void svm_vcpu_init_msrpm(u32 *msrpm)
+{
+	memset(msrpm, 0xff, PAGE_SIZE * (1 << MSRPM_ALLOC_ORDER));
+
+#ifdef CONFIG_X86_64
+	set_msr_interception(msrpm, MSR_GS_BASE, 1, 1);
+	set_msr_interception(msrpm, MSR_FS_BASE, 1, 1);
+	set_msr_interception(msrpm, MSR_KERNEL_GS_BASE, 1, 1);
+	set_msr_interception(msrpm, MSR_LSTAR, 1, 1);
+	set_msr_interception(msrpm, MSR_CSTAR, 1, 1);
+	set_msr_interception(msrpm, MSR_SYSCALL_MASK, 1, 1);
+#endif
+	set_msr_interception(msrpm, MSR_K6_STAR, 1, 1);
+	set_msr_interception(msrpm, MSR_IA32_SYSENTER_CS, 1, 1);
+	set_msr_interception(msrpm, MSR_IA32_SYSENTER_ESP, 1, 1);
+	set_msr_interception(msrpm, MSR_IA32_SYSENTER_EIP, 1, 1);
+}
+
 static __init int svm_hardware_setup(void)
 {
 	int cpu;
 	struct page *iopm_pages;
-	struct page *msrpm_pages;
-	void *iopm_va, *msrpm_va;
+	void *iopm_va;
 	int r;
 
 	iopm_pages = alloc_pages(GFP_KERNEL, IOPM_ALLOC_ORDER);
@@ -388,37 +404,13 @@ static __init int svm_hardware_setup(void)
 	clear_bit(0x80, iopm_va); /* allow direct access to PC debug port */
 	iopm_base = page_to_pfn(iopm_pages) << PAGE_SHIFT;
 
-
-	msrpm_pages = alloc_pages(GFP_KERNEL, MSRPM_ALLOC_ORDER);
-
-	r = -ENOMEM;
-	if (!msrpm_pages)
-		goto err_1;
-
-	msrpm_va = page_address(msrpm_pages);
-	memset(msrpm_va, 0xff, PAGE_SIZE * (1 << MSRPM_ALLOC_ORDER));
-	msrpm_base = page_to_pfn(msrpm_pages) << PAGE_SHIFT;
-
-#ifdef CONFIG_X86_64
-	set_msr_interception(msrpm_va, MSR_GS_BASE, 1, 1);
-	set_msr_interception(msrpm_va, MSR_FS_BASE, 1, 1);
-	set_msr_interception(msrpm_va, MSR_KERNEL_GS_BASE, 1, 1);
-	set_msr_interception(msrpm_va, MSR_LSTAR, 1, 1);
-	set_msr_interception(msrpm_va, MSR_CSTAR, 1, 1);
-	set_msr_interception(msrpm_va, MSR_SYSCALL_MASK, 1, 1);
-#endif
-	set_msr_interception(msrpm_va, MSR_K6_STAR, 1, 1);
-	set_msr_interception(msrpm_va, MSR_IA32_SYSENTER_CS, 1, 1);
-	set_msr_interception(msrpm_va, MSR_IA32_SYSENTER_ESP, 1, 1);
-	set_msr_interception(msrpm_va, MSR_IA32_SYSENTER_EIP, 1, 1);
-
 	if (boot_cpu_has(X86_FEATURE_NX))
 		kvm_enable_efer_bits(EFER_NX);
 
 	for_each_online_cpu(cpu) {
 		r = svm_cpu_init(cpu);
 		if (r)
-			goto err_2;
+			goto err;
 	}
 
 	svm_features = cpuid_edx(SVM_CPUID_FUNC);
@@ -438,10 +430,7 @@ static __init int svm_hardware_setup(void)
 
 	return 0;
 
-err_2:
-	__free_pages(msrpm_pages, MSRPM_ALLOC_ORDER);
-	msrpm_base = 0;
-err_1:
+err:
 	__free_pages(iopm_pages, IOPM_ALLOC_ORDER);
 	iopm_base = 0;
 	return r;
@@ -449,9 +438,8 @@ err_1:
 
 static __exit void svm_hardware_unsetup(void)
 {
-	__free_pages(pfn_to_page(msrpm_base >> PAGE_SHIFT), MSRPM_ALLOC_ORDER);
 	__free_pages(pfn_to_page(iopm_base >> PAGE_SHIFT), IOPM_ALLOC_ORDER);
-	iopm_base = msrpm_base = 0;
+	iopm_base = 0;
 }
 
 static void init_seg(struct vmcb_seg *seg)
@@ -536,7 +524,7 @@ static void init_vmcb(struct vcpu_svm *svm)
 				(1ULL << INTERCEPT_MWAIT);
 
 	control->iopm_base_pa = iopm_base;
-	control->msrpm_base_pa = msrpm_base;
+	control->msrpm_base_pa = __pa(svm->msrpm);
 	control->tsc_offset = 0;
 	control->int_ctl = V_INTR_MASKING_MASK;
 
@@ -615,6 +603,7 @@ static struct kvm_vcpu *svm_create_vcpu(struct kvm *kvm, unsigned int id)
 {
 	struct vcpu_svm *svm;
 	struct page *page;
+	struct page *msrpm_pages;
 	int err;
 
 	svm = kmem_cache_zalloc(kvm_vcpu_cache, GFP_KERNEL);
@@ -633,6 +622,13 @@ static struct kvm_vcpu *svm_create_vcpu(struct kvm *kvm, unsigned int id)
 		goto uninit;
 	}
 
+	err = -ENOMEM;
+	msrpm_pages = alloc_pages(GFP_KERNEL, MSRPM_ALLOC_ORDER);
+	if (!msrpm_pages)
+		goto uninit;
+	svm->msrpm = page_address(msrpm_pages);
+	svm_vcpu_init_msrpm(svm->msrpm);
+
 	svm->vmcb = page_address(page);
 	clear_page(svm->vmcb);
 	svm->vmcb_pa = page_to_pfn(page) << PAGE_SHIFT;
@@ -661,6 +657,7 @@ static void svm_free_vcpu(struct kvm_vcpu *vcpu)
 	struct vcpu_svm *svm = to_svm(vcpu);
 
 	__free_page(pfn_to_page(svm->vmcb_pa >> PAGE_SHIFT));
+	__free_pages(virt_to_page(svm->msrpm), MSRPM_ALLOC_ORDER);
 	kvm_vcpu_uninit(vcpu);
 	kmem_cache_free(kvm_vcpu_cache, svm);
 }
-- 
1.5.3.7




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[PATCH 3/3] KVM: SVM: enable LBR virtualization

[Joerg Roedel]

This patch implements the Last Branch Record Virtualization (LBRV) feature of
the AMD Barcelona and Phenom processors into the kvm-amd module. It will only
be enabled if the guest enables last branch recording in the DEBUG_CTL MSR. So
there is no increased world switch overhead when the guest doesn't use these
MSRs.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Markus Rechberger <markus.rechberger@amd.com>
---
 arch/x86/kvm/svm.c |   39 +++++++++++++++++++++++++++++++++++++--
 1 files changed, 37 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 3b31162..e1d139f 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -47,6 +47,8 @@ MODULE_LICENSE("GPL");
 #define SVM_FEATURE_LBRV (1 << 1)
 #define SVM_DEATURE_SVML (1 << 2)
 
+#define DEBUGCTL_RESERVED_BITS (~(0x3fULL))
+
 /* enable NPT for AMD64 and X86 with PAE */
 #if defined(CONFIG_X86_64) || defined(CONFIG_X86_PAE)
 static bool npt_enabled = true;
@@ -387,6 +389,28 @@ static void svm_vcpu_init_msrpm(u32 *msrpm)
 	set_msr_interception(msrpm, MSR_IA32_SYSENTER_EIP, 1, 1);
 }
 
+static void svm_enable_lbrv(struct vcpu_svm *svm)
+{
+	u32 *msrpm = svm->msrpm;
+
+	svm->vmcb->control.lbr_ctl = 1;
+	set_msr_interception(msrpm, MSR_IA32_LASTBRANCHFROMIP, 1, 1);
+	set_msr_interception(msrpm, MSR_IA32_LASTBRANCHTOIP, 1, 1);
+	set_msr_interception(msrpm, MSR_IA32_LASTINTFROMIP, 1, 1);
+	set_msr_interception(msrpm, MSR_IA32_LASTINTTOIP, 1, 1);
+}
+
+static void svm_disable_lbrv(struct vcpu_svm *svm)
+{
+	u32 *msrpm = svm->msrpm;
+
+	svm->vmcb->control.lbr_ctl = 0;
+	set_msr_interception(msrpm, MSR_IA32_LASTBRANCHFROMIP, 0, 0);
+	set_msr_interception(msrpm, MSR_IA32_LASTBRANCHTOIP, 0, 0);
+	set_msr_interception(msrpm, MSR_IA32_LASTINTFROMIP, 0, 0);
+	set_msr_interception(msrpm, MSR_IA32_LASTINTTOIP, 0, 0);
+}
+
 static __init int svm_hardware_setup(void)
 {
 	int cpu;
@@ -1231,8 +1255,19 @@ static int svm_set_msr(struct kvm_vcpu *vcpu, unsigned ecx, u64 data)
 		svm->vmcb->save.sysenter_esp = data;
 		break;
 	case MSR_IA32_DEBUGCTLMSR:
-		pr_unimpl(vcpu, "%s: MSR_IA32_DEBUGCTLMSR 0x%llx, nop\n",
-				__FUNCTION__, data);
+		if (!svm_has(SVM_FEATURE_LBRV)) {
+			pr_unimpl(vcpu, "%s: MSR_IA32_DEBUGCTL 0x%llx, nop\n",
+					__FUNCTION__, data);
+			break;
+		}
+		if (data & DEBUGCTL_RESERVED_BITS)
+			return 1;
+
+		svm->vmcb->save.dbgctl = data;
+		if (data & (1ULL<<0))
+			svm_enable_lbrv(svm);
+		else
+			svm_disable_lbrv(svm);
 		break;
 	case MSR_K7_EVNTSEL0:
 	case MSR_K7_EVNTSEL1:
-- 
1.5.3.7




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Re: KVM: SVM: Implement LBR virtualization

[Avi Kivity]

Joerg Roedel wrote:
> This patch set enables the virtualization of the last branch record in SVM if
> this feature is supported by the hardware. To the previous post the fix for the
> XP 64 bit install crash has been removed from this series and was posted
> seperatly to keep it small enough for 2.6.25. This patch set applies on top of
> that fix.
>   

Applied, thanks.

-- 
Any sufficiently difficult bug is indistinguishable from a feature.


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