[PULL 10/23] target/i386: Add MSR access interface for Arch LBR

[Paolo Bonzini]

From: Yang Weijiang <weijiang.yang@intel.com>

In the first generation of Arch LBR, the max support
Arch LBR depth is 32, both host and guest use the value
to set depth MSR. This can simplify the implementation
of patch given the side-effect of mismatch of host/guest
depth MSR: XRSTORS will reset all recording MSRs to 0s
if the saved depth mismatches MSR_ARCH_LBR_DEPTH.

In most of the cases Arch LBR is not in active status,
so check the control bit before save/restore the big
chunck of Arch LBR MSRs.

Signed-off-by: Yang Weijiang <weijiang.yang@intel.com>
Message-Id: <20220215195258.29149-7-weijiang.yang@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 target/i386/cpu.h     | 10 +++++++
 target/i386/kvm/kvm.c | 67 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 77 insertions(+)

diff --git a/target/i386/cpu.h b/target/i386/cpu.h
index dba92936a2..0d528ac58f 100644
--- a/target/i386/cpu.h
+++ b/target/i386/cpu.h
@@ -391,6 +391,11 @@ typedef enum X86Seg {
 #define MSR_IA32_TSX_CTRL              0x122
 #define MSR_IA32_TSCDEADLINE            0x6e0
 #define MSR_IA32_PKRS                   0x6e1
+#define MSR_ARCH_LBR_CTL                0x000014ce
+#define MSR_ARCH_LBR_DEPTH              0x000014cf
+#define MSR_ARCH_LBR_FROM_0             0x00001500
+#define MSR_ARCH_LBR_TO_0               0x00001600
+#define MSR_ARCH_LBR_INFO_0             0x00001200
 
 #define FEATURE_CONTROL_LOCKED                    (1<<0)
 #define FEATURE_CONTROL_VMXON_ENABLED_INSIDE_SMX  (1ULL << 1)
@@ -1650,6 +1655,11 @@ typedef struct CPUArchState {
     uint64_t msr_xfd;
     uint64_t msr_xfd_err;
 
+    /* Per-VCPU Arch LBR MSRs */
+    uint64_t msr_lbr_ctl;
+    uint64_t msr_lbr_depth;
+    LBREntry lbr_records[ARCH_LBR_NR_ENTRIES];
+
     /* exception/interrupt handling */
     int error_code;
     int exception_is_int;
diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c
index 536cbe5fad..a9ee8eebd7 100644
--- a/target/i386/kvm/kvm.c
+++ b/target/i386/kvm/kvm.c
@@ -3367,6 +3367,38 @@ static int kvm_put_msrs(X86CPU *cpu, int level)
                               env->msr_xfd_err);
         }
 
+        if (kvm_enabled() && cpu->enable_pmu &&
+            (env->features[FEAT_7_0_EDX] & CPUID_7_0_EDX_ARCH_LBR)) {
+            uint64_t depth;
+            int i, ret;
+
+            /*
+             * Only migrate Arch LBR states when: 1) Arch LBR is enabled
+             * for migrated vcpu. 2) the host Arch LBR depth equals that
+             * of source guest's, this is to avoid mismatch of guest/host
+             * config for the msr hence avoid unexpected misbehavior.
+             */
+            ret = kvm_get_one_msr(cpu, MSR_ARCH_LBR_DEPTH, &depth);
+
+            if (ret == 1 && (env->msr_lbr_ctl & 0x1) && !!depth &&
+                depth == env->msr_lbr_depth) {
+                kvm_msr_entry_add(cpu, MSR_ARCH_LBR_CTL, env->msr_lbr_ctl);
+                kvm_msr_entry_add(cpu, MSR_ARCH_LBR_DEPTH, env->msr_lbr_depth);
+
+                for (i = 0; i < ARCH_LBR_NR_ENTRIES; i++) {
+                    if (!env->lbr_records[i].from) {
+                        continue;
+                    }
+                    kvm_msr_entry_add(cpu, MSR_ARCH_LBR_FROM_0 + i,
+                                      env->lbr_records[i].from);
+                    kvm_msr_entry_add(cpu, MSR_ARCH_LBR_TO_0 + i,
+                                      env->lbr_records[i].to);
+                    kvm_msr_entry_add(cpu, MSR_ARCH_LBR_INFO_0 + i,
+                                      env->lbr_records[i].info);
+                }
+            }
+        }
+
         /* Note: MSR_IA32_FEATURE_CONTROL is written separately, see
          *       kvm_put_msr_feature_control. */
     }
@@ -3767,6 +3799,26 @@ static int kvm_get_msrs(X86CPU *cpu)
         kvm_msr_entry_add(cpu, MSR_IA32_XFD_ERR, 0);
     }
 
+    if (kvm_enabled() && cpu->enable_pmu &&
+        (env->features[FEAT_7_0_EDX] & CPUID_7_0_EDX_ARCH_LBR)) {
+        uint64_t ctl, depth;
+        int i, ret2;
+
+        ret = kvm_get_one_msr(cpu, MSR_ARCH_LBR_CTL, &ctl);
+        ret2 = kvm_get_one_msr(cpu, MSR_ARCH_LBR_DEPTH, &depth);
+        if (ret == 1 && ret2 == 1 && (ctl & 0x1) &&
+            depth == ARCH_LBR_NR_ENTRIES) {
+            kvm_msr_entry_add(cpu, MSR_ARCH_LBR_CTL, 0);
+            kvm_msr_entry_add(cpu, MSR_ARCH_LBR_DEPTH, 0);
+
+            for (i = 0; i < ARCH_LBR_NR_ENTRIES; i++) {
+                kvm_msr_entry_add(cpu, MSR_ARCH_LBR_FROM_0 + i, 0);
+                kvm_msr_entry_add(cpu, MSR_ARCH_LBR_TO_0 + i, 0);
+                kvm_msr_entry_add(cpu, MSR_ARCH_LBR_INFO_0 + i, 0);
+            }
+        }
+    }
+
     ret = kvm_vcpu_ioctl(CPU(cpu), KVM_GET_MSRS, cpu->kvm_msr_buf);
     if (ret < 0) {
         return ret;
@@ -4072,6 +4124,21 @@ static int kvm_get_msrs(X86CPU *cpu)
         case MSR_IA32_XFD_ERR:
             env->msr_xfd_err = msrs[i].data;
             break;
+        case MSR_ARCH_LBR_CTL:
+            env->msr_lbr_ctl = msrs[i].data;
+            break;
+        case MSR_ARCH_LBR_DEPTH:
+            env->msr_lbr_depth = msrs[i].data;
+            break;
+        case MSR_ARCH_LBR_FROM_0 ... MSR_ARCH_LBR_FROM_0 + 31:
+            env->lbr_records[index - MSR_ARCH_LBR_FROM_0].from = msrs[i].data;
+            break;
+        case MSR_ARCH_LBR_TO_0 ... MSR_ARCH_LBR_TO_0 + 31:
+            env->lbr_records[index - MSR_ARCH_LBR_TO_0].to = msrs[i].data;
+            break;
+        case MSR_ARCH_LBR_INFO_0 ... MSR_ARCH_LBR_INFO_0 + 31:
+            env->lbr_records[index - MSR_ARCH_LBR_INFO_0].info = msrs[i].data;
+            break;
         }
     }
 
-- 
2.36.0