[PATCH v7 11/15] KVM: x86/vmx: Check Arch LBR config when return perf capabilities

From: Yang Weijiang
Date: Fri Aug 06 2021 - 03:30:26 EST


Two new bit fields(VM_EXIT_CLEAR_IA32_LBR_CTL, VM_ENTRY_LOAD_IA32_LBR_CTL)
are added to support guest Arch LBR. These two bits should be set in order
to make Arch LBR workable in both guest and host.

Co-developed-by: Like Xu <like.xu@xxxxxxxxxxxxxxx>
Signed-off-by: Like Xu <like.xu@xxxxxxxxxxxxxxx>
Signed-off-by: Yang Weijiang <weijiang.yang@xxxxxxxxx>
---
arch/x86/include/asm/vmx.h | 2 ++
arch/x86/kvm/vmx/capabilities.h | 25 +++++++++++++++++--------
arch/x86/kvm/vmx/vmx.c | 6 ++++--
3 files changed, 23 insertions(+), 10 deletions(-)

diff --git a/arch/x86/include/asm/vmx.h b/arch/x86/include/asm/vmx.h
index ea3be961cc8e..d9b1dffc4638 100644
--- a/arch/x86/include/asm/vmx.h
+++ b/arch/x86/include/asm/vmx.h
@@ -95,6 +95,7 @@
#define VM_EXIT_CLEAR_BNDCFGS 0x00800000
#define VM_EXIT_PT_CONCEAL_PIP 0x01000000
#define VM_EXIT_CLEAR_IA32_RTIT_CTL 0x02000000
+#define VM_EXIT_CLEAR_IA32_LBR_CTL 0x04000000

#define VM_EXIT_ALWAYSON_WITHOUT_TRUE_MSR 0x00036dff

@@ -108,6 +109,7 @@
#define VM_ENTRY_LOAD_BNDCFGS 0x00010000
#define VM_ENTRY_PT_CONCEAL_PIP 0x00020000
#define VM_ENTRY_LOAD_IA32_RTIT_CTL 0x00040000
+#define VM_ENTRY_LOAD_IA32_LBR_CTL 0x00200000

#define VM_ENTRY_ALWAYSON_WITHOUT_TRUE_MSR 0x000011ff

diff --git a/arch/x86/kvm/vmx/capabilities.h b/arch/x86/kvm/vmx/capabilities.h
index 4705ad55abb5..51855a559a75 100644
--- a/arch/x86/kvm/vmx/capabilities.h
+++ b/arch/x86/kvm/vmx/capabilities.h
@@ -376,20 +376,29 @@ static inline bool vmx_pt_mode_is_host_guest(void)
return pt_mode == PT_MODE_HOST_GUEST;
}

-static inline u64 vmx_get_perf_capabilities(void)
+static inline bool cpu_has_vmx_arch_lbr(void)
{
- u64 perf_cap = 0;
-
- if (boot_cpu_has(X86_FEATURE_PDCM))
- rdmsrl(MSR_IA32_PERF_CAPABILITIES, perf_cap);
-
- perf_cap &= PMU_CAP_LBR_FMT;
+ return (vmcs_config.vmexit_ctrl & VM_EXIT_CLEAR_IA32_LBR_CTL) &&
+ (vmcs_config.vmentry_ctrl & VM_ENTRY_LOAD_IA32_LBR_CTL);
+}

+static inline u64 vmx_get_perf_capabilities(void)
+{
/*
* Since counters are virtualized, KVM would support full
* width counting unconditionally, even if the host lacks it.
*/
- return PMU_CAP_FW_WRITES | perf_cap;
+ u64 perf_cap = PMU_CAP_FW_WRITES;
+ u64 host_perf_cap = 0;
+
+ if (boot_cpu_has(X86_FEATURE_PDCM))
+ rdmsrl(MSR_IA32_PERF_CAPABILITIES, host_perf_cap);
+
+ perf_cap |= host_perf_cap & PMU_CAP_LBR_FMT;
+ if (boot_cpu_has(X86_FEATURE_ARCH_LBR) && !cpu_has_vmx_arch_lbr())
+ perf_cap &= ~PMU_CAP_LBR_FMT;
+
+ return perf_cap;
}

static inline u64 vmx_supported_debugctl(void)
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 5f0545106d54..70314cd93340 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -2513,7 +2513,8 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf,
VM_EXIT_LOAD_IA32_EFER |
VM_EXIT_CLEAR_BNDCFGS |
VM_EXIT_PT_CONCEAL_PIP |
- VM_EXIT_CLEAR_IA32_RTIT_CTL;
+ VM_EXIT_CLEAR_IA32_RTIT_CTL |
+ VM_EXIT_CLEAR_IA32_LBR_CTL;
if (adjust_vmx_controls(min, opt, MSR_IA32_VMX_EXIT_CTLS,
&_vmexit_control) < 0)
return -EIO;
@@ -2537,7 +2538,8 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf,
VM_ENTRY_LOAD_IA32_EFER |
VM_ENTRY_LOAD_BNDCFGS |
VM_ENTRY_PT_CONCEAL_PIP |
- VM_ENTRY_LOAD_IA32_RTIT_CTL;
+ VM_ENTRY_LOAD_IA32_RTIT_CTL |
+ VM_ENTRY_LOAD_IA32_LBR_CTL;
if (adjust_vmx_controls(min, opt, MSR_IA32_VMX_ENTRY_CTLS,
&_vmentry_control) < 0)
return -EIO;
--
2.25.1