[Xen-changelog] [xen-unstable] x86 hvm: New boot option 'softtsc' to cause RDTSC to be trapped-and-emulated.

[Xen patchbot-unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1215701118 -3600
# Node ID f454f2cac170a511b6727f84a8032a8132e05d84
# Parent  b7598d2e479198399ae0a91ca5d8779df14e5a8b
x86 hvm: New boot option 'softtsc' to cause RDTSC to be trapped-and-emulated.

Signed-off-by: Dan Magenheimer <dan.magenheimer@xxxxxxxxxx>
Signed-off-by: Keir Fraser <keir.fraser@xxxxxxxxxx>
---
 xen/arch/x86/hvm/hvm.c            |   19 ++++++++++++++++++-
 xen/arch/x86/hvm/svm/svm.c        |    4 ++++
 xen/arch/x86/hvm/svm/vmcb.c       |    4 +++-
 xen/arch/x86/hvm/vmx/vmcs.c       |    3 ++-
 xen/arch/x86/hvm/vmx/vmx.c        |    5 +++++
 xen/include/asm-x86/hvm/support.h |    3 +++
 6 files changed, 35 insertions(+), 3 deletions(-)

diff -r b7598d2e4791 -r f454f2cac170 xen/arch/x86/hvm/hvm.c
--- a/xen/arch/x86/hvm/hvm.c    Thu Jul 10 15:32:18 2008 +0100
+++ b/xen/arch/x86/hvm/hvm.c    Thu Jul 10 15:45:18 2008 +0100
@@ -57,6 +57,9 @@ unsigned int opt_hvm_debug_level __read_
 unsigned int opt_hvm_debug_level __read_mostly;
 integer_param("hvm_debug", opt_hvm_debug_level);
 
+int opt_softtsc;
+boolean_param("softtsc", opt_softtsc);
+
 struct hvm_function_table hvm_funcs __read_mostly;
 
 /* I/O permission bitmap is globally shared by all HVM guests. */
@@ -148,7 +151,11 @@ u64 hvm_get_guest_tsc(struct vcpu *v)
 {
     u64 host_tsc;
 
-    rdtscll(host_tsc);
+    if ( opt_softtsc )
+        host_tsc = hvm_get_guest_time(v);
+    else
+        rdtscll(host_tsc);
+
     return host_tsc + v->arch.hvm_vcpu.cache_tsc_offset;
 }
 
@@ -1649,6 +1656,16 @@ void hvm_cpuid(unsigned int input, unsig
         if ( vlapic_hw_disabled(vcpu_vlapic(v)) )
             __clear_bit(X86_FEATURE_APIC & 31, edx);
     }
+}
+
+void hvm_rdtsc_intercept(struct cpu_user_regs *regs)
+{
+    uint64_t tsc;
+    struct vcpu *v = current;
+
+    tsc = hvm_get_guest_tsc(v);
+    regs->eax = (uint32_t)tsc;
+    regs->edx = (uint32_t)(tsc >> 32);
 }
 
 int hvm_msr_read_intercept(struct cpu_user_regs *regs)
diff -r b7598d2e4791 -r f454f2cac170 xen/arch/x86/hvm/svm/svm.c
--- a/xen/arch/x86/hvm/svm/svm.c        Thu Jul 10 15:32:18 2008 +0100
+++ b/xen/arch/x86/hvm/svm/svm.c        Thu Jul 10 15:45:18 2008 +0100
@@ -1340,6 +1340,10 @@ asmlinkage void svm_vmexit_handler(struc
         hvm_triple_fault();
         break;
 
+    case VMEXIT_RDTSC:
+        hvm_rdtsc_intercept(regs);
+        break;
+
     case VMEXIT_RDTSCP:
     case VMEXIT_MONITOR:
     case VMEXIT_MWAIT:
diff -r b7598d2e4791 -r f454f2cac170 xen/arch/x86/hvm/svm/vmcb.c
--- a/xen/arch/x86/hvm/svm/vmcb.c       Thu Jul 10 15:32:18 2008 +0100
+++ b/xen/arch/x86/hvm/svm/vmcb.c       Thu Jul 10 15:45:18 2008 +0100
@@ -165,7 +165,9 @@ static int construct_vmcb(struct vcpu *v
 
     /* TSC. */
     vmcb->tsc_offset = 0;
-    
+    if ( opt_softtsc )
+        vmcb->general1_intercepts |= GENERAL1_INTERCEPT_RDTSC;
+
     /* Guest EFER: *must* contain SVME or VMRUN will fail. */
     vmcb->efer = EFER_SVME;
 
diff -r b7598d2e4791 -r f454f2cac170 xen/arch/x86/hvm/vmx/vmcs.c
--- a/xen/arch/x86/hvm/vmx/vmcs.c       Thu Jul 10 15:32:18 2008 +0100
+++ b/xen/arch/x86/hvm/vmx/vmcs.c       Thu Jul 10 15:45:18 2008 +0100
@@ -95,7 +95,8 @@ static void vmx_init_vmcs_config(void)
            CPU_BASED_MWAIT_EXITING |
            CPU_BASED_MOV_DR_EXITING |
            CPU_BASED_ACTIVATE_IO_BITMAP |
-           CPU_BASED_USE_TSC_OFFSETING);
+           CPU_BASED_USE_TSC_OFFSETING |
+           (opt_softtsc ? CPU_BASED_RDTSC_EXITING : 0));
     opt = (CPU_BASED_ACTIVATE_MSR_BITMAP |
            CPU_BASED_TPR_SHADOW |
            CPU_BASED_ACTIVATE_SECONDARY_CONTROLS);
diff -r b7598d2e4791 -r f454f2cac170 xen/arch/x86/hvm/vmx/vmx.c
--- a/xen/arch/x86/hvm/vmx/vmx.c        Thu Jul 10 15:32:18 2008 +0100
+++ b/xen/arch/x86/hvm/vmx/vmx.c        Thu Jul 10 15:45:18 2008 +0100
@@ -2205,6 +2205,11 @@ asmlinkage void vmx_vmexit_handler(struc
         vmx_invlpg_intercept(exit_qualification);
         break;
     }
+    case EXIT_REASON_RDTSC:
+        inst_len = __get_instruction_length();
+        __update_guest_eip(inst_len);
+        hvm_rdtsc_intercept(regs);
+        break;
     case EXIT_REASON_VMCALL:
     {
         int rc;
diff -r b7598d2e4791 -r f454f2cac170 xen/include/asm-x86/hvm/support.h
--- a/xen/include/asm-x86/hvm/support.h Thu Jul 10 15:32:18 2008 +0100
+++ b/xen/include/asm-x86/hvm/support.h Thu Jul 10 15:45:18 2008 +0100
@@ -125,6 +125,9 @@ void hvm_hlt(unsigned long rflags);
 void hvm_hlt(unsigned long rflags);
 void hvm_triple_fault(void);
 
+extern int opt_softtsc;
+void hvm_rdtsc_intercept(struct cpu_user_regs *regs);
+
 /* These functions all return X86EMUL return codes. */
 int hvm_set_efer(uint64_t value);
 int hvm_set_cr0(unsigned long value);

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