File 63a03b73-VMX-VMExit-based-BusLock-detection.patch of Package xen

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File 63a03b73-VMX-VMExit-based-BusLock-detection.patch of Package xen (Revision bfadaa722ca78042251d7971c9d5deeb)

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# Commit f7d07619d2ae0382e2922e287fbfbb27722f3f0b
# Date 2022-12-19 11:22:43 +0100
# Author Roger Pau Monné <roger.pau@citrix.com>
# Committer Jan Beulich <jbeulich@suse.com>
x86/vmx: implement VMExit based guest Bus Lock detection

Add support for enabling guest Bus Lock Detection on Intel systems.
Such detection works by triggering a vmexit, which ought to be enough
of a pause to prevent a guest from abusing of the Bus Lock.

Add an extra Xen perf counter to track the number of Bus Locks detected.
This is done because Bus Locks can also be reported by setting the bit
26 in the exit reason field, so also account for those.

Note EXIT_REASON_BUS_LOCK VMExits will always have bit 26 set in
exit_reason, and hence the performance counter doesn't need to be
increased for EXIT_REASON_BUS_LOCK handling.

Suggested-by: Andrew Cooper <andrew.cooper3@citrix.com>
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>

--- a/xen/arch/x86/hvm/vmx/vmcs.c
+++ b/xen/arch/x86/hvm/vmx/vmcs.c
@@ -209,6 +209,7 @@ static void __init vmx_display_features(
     P(cpu_has_vmx_virt_exceptions, "Virtualisation Exceptions");
     P(cpu_has_vmx_pml, "Page Modification Logging");
     P(cpu_has_vmx_tsc_scaling, "TSC Scaling");
+    P(cpu_has_vmx_bus_lock_detection, "Bus Lock Detection");
 #undef P
 
     if ( !printed )
@@ -318,7 +319,8 @@ static int vmx_init_vmcs_config(bool bsp
                SECONDARY_EXEC_ENABLE_VM_FUNCTIONS |
                SECONDARY_EXEC_ENABLE_VIRT_EXCEPTIONS |
                SECONDARY_EXEC_XSAVES |
-               SECONDARY_EXEC_TSC_SCALING);
+               SECONDARY_EXEC_TSC_SCALING |
+               SECONDARY_EXEC_BUS_LOCK_DETECTION);
         if ( _vmx_misc_cap & VMX_MISC_VMWRITE_ALL )
             opt |= SECONDARY_EXEC_ENABLE_VMCS_SHADOWING;
         if ( opt_vpid_enabled )
--- a/xen/arch/x86/hvm/vmx/vmx.c
+++ b/xen/arch/x86/hvm/vmx/vmx.c
@@ -4081,6 +4081,12 @@ void vmx_vmexit_handler(struct cpu_user_
             return;
     }
 
+    if ( unlikely(exit_reason & VMX_EXIT_REASONS_BUS_LOCK) )
+    {
+        perfc_incr(buslock);
+        exit_reason &= ~VMX_EXIT_REASONS_BUS_LOCK;
+    }
+
     /* XXX: This looks ugly, but we need a mechanism to ensure
      * any pending vmresume has really happened
      */
@@ -4590,6 +4596,15 @@ void vmx_vmexit_handler(struct cpu_user_
         vmx_handle_descriptor_access(exit_reason);
         break;
 
+    case EXIT_REASON_BUS_LOCK:
+        /*
+         * Nothing to do: just taking a vmexit should be enough of a pause to
+         * prevent a VM from crippling the host with bus locks.  Note
+         * EXIT_REASON_BUS_LOCK will always have bit 26 set in exit_reason, and
+         * hence the perf counter is already increased.
+         */
+        break;
+
     case EXIT_REASON_VMX_PREEMPTION_TIMER_EXPIRED:
     case EXIT_REASON_INVPCID:
     /* fall through */
--- a/xen/arch/x86/hvm/vmx/vvmx.c
+++ b/xen/arch/x86/hvm/vmx/vvmx.c
@@ -2405,7 +2405,7 @@ void nvmx_idtv_handling(void)
      * be reinjected, otherwise, pass to L1.
      */
     __vmread(VM_EXIT_REASON, &reason);
-    if ( reason != EXIT_REASON_EPT_VIOLATION ?
+    if ( (uint16_t)reason != EXIT_REASON_EPT_VIOLATION ?
          !(nvmx->intr.intr_info & INTR_INFO_VALID_MASK) :
          !nvcpu->nv_vmexit_pending )
     {
@@ -2486,6 +2486,7 @@ int nvmx_n2_vmexit_handler(struct cpu_us
     case EXIT_REASON_EPT_VIOLATION:
     case EXIT_REASON_EPT_MISCONFIG:
     case EXIT_REASON_EXTERNAL_INTERRUPT:
+    case EXIT_REASON_BUS_LOCK:
         /* pass to L0 handler */
         break;
     case VMX_EXIT_REASONS_FAILED_VMENTRY:
--- a/xen/arch/x86/include/asm/hvm/vmx/vmcs.h
+++ b/xen/arch/x86/include/asm/hvm/vmx/vmcs.h
@@ -267,6 +267,7 @@ extern u32 vmx_vmentry_control;
 #define SECONDARY_EXEC_ENABLE_VIRT_EXCEPTIONS   0x00040000
 #define SECONDARY_EXEC_XSAVES                   0x00100000
 #define SECONDARY_EXEC_TSC_SCALING              0x02000000
+#define SECONDARY_EXEC_BUS_LOCK_DETECTION       0x40000000
 extern u32 vmx_secondary_exec_control;
 
 #define VMX_EPT_EXEC_ONLY_SUPPORTED                         0x00000001
@@ -346,6 +347,8 @@ extern u64 vmx_ept_vpid_cap;
     (vmx_secondary_exec_control & SECONDARY_EXEC_XSAVES)
 #define cpu_has_vmx_tsc_scaling \
     (vmx_secondary_exec_control & SECONDARY_EXEC_TSC_SCALING)
+#define cpu_has_vmx_bus_lock_detection \
+    (vmx_secondary_exec_control & SECONDARY_EXEC_BUS_LOCK_DETECTION)
 
 #define VMCS_RID_TYPE_MASK              0x80000000
 
--- a/xen/arch/x86/include/asm/hvm/vmx/vmx.h
+++ b/xen/arch/x86/include/asm/hvm/vmx/vmx.h
@@ -159,6 +159,7 @@ static inline void pi_clear_sn(struct pi
  * Exit Reasons
  */
 #define VMX_EXIT_REASONS_FAILED_VMENTRY 0x80000000
+#define VMX_EXIT_REASONS_BUS_LOCK       (1u << 26)
 
 #define EXIT_REASON_EXCEPTION_NMI       0
 #define EXIT_REASON_EXTERNAL_INTERRUPT  1
@@ -219,6 +220,7 @@ static inline void pi_clear_sn(struct pi
 #define EXIT_REASON_PML_FULL            62
 #define EXIT_REASON_XSAVES              63
 #define EXIT_REASON_XRSTORS             64
+#define EXIT_REASON_BUS_LOCK            74
 /* Remember to also update VMX_PERF_EXIT_REASON_SIZE! */
 
 /*
--- a/xen/arch/x86/include/asm/perfc_defn.h
+++ b/xen/arch/x86/include/asm/perfc_defn.h
@@ -6,7 +6,7 @@ PERFCOUNTER_ARRAY(exceptions,
 
 #ifdef CONFIG_HVM
 
-#define VMX_PERF_EXIT_REASON_SIZE 65
+#define VMX_PERF_EXIT_REASON_SIZE 75
 #define VMEXIT_NPF_PERFC 143
 #define SVM_PERF_EXIT_REASON_SIZE (VMEXIT_NPF_PERFC + 1)
 PERFCOUNTER_ARRAY(vmexits,              "vmexits",
@@ -128,4 +128,6 @@ PERFCOUNTER(pauseloop_exits, "vmexits fr
 PERFCOUNTER(iommu_pt_shatters,    "IOMMU page table shatters")
 PERFCOUNTER(iommu_pt_coalesces,   "IOMMU page table coalesces")
 
+PERFCOUNTER(buslock, "Bus Locks Detected")
+
 /*#endif*/ /* __XEN_PERFC_DEFN_H__ */

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File 63a03b73-VMX-VMExit-based-BusLock-detection.patch of Package xen (Revision bfadaa722ca78042251d7971c9d5deeb)

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