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Subjectkvm: RDTSCP on AMD
Hi guys,

how about this below to enable RDTSCP emulation on AMD? IOW, I'm staring
at

33b5e8c03ae7 ("target-i386: Disable rdtscp on Opteron_G* CPU models")

in the qemu repo.

It seems to work here, RDTSCP in the guest gives me node and cpu as
vsyscall_set_cpu() in the guest kernel has set them.

Thoughts?

(Below is the simple qemu diff reenabling RDTSCP)

---
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 16ef31b87452..5a238f5402f5 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -1131,6 +1131,7 @@ static void init_vmcb(struct vcpu_svm *svm)
set_intercept(svm, INTERCEPT_STGI);
set_intercept(svm, INTERCEPT_CLGI);
set_intercept(svm, INTERCEPT_SKINIT);
+ set_intercept(svm, INTERCEPT_RDTSCP);
set_intercept(svm, INTERCEPT_WBINVD);
set_intercept(svm, INTERCEPT_MONITOR);
set_intercept(svm, INTERCEPT_MWAIT);
@@ -3009,6 +3010,20 @@ static int skinit_interception(struct vcpu_svm *svm)
return 1;
}

+static int rdtscp_interception(struct vcpu_svm *svm)
+{
+ u64 tsc;
+
+ tsc = kvm_scale_tsc(&svm->vcpu, rdtsc()) + svm->vmcb->control.tsc_offset;
+
+ kvm_register_write(&svm->vcpu, VCPU_REGS_RAX, tsc & 0xffffffff);
+ kvm_register_write(&svm->vcpu, VCPU_REGS_RDX, tsc >> 32);
+ kvm_register_write(&svm->vcpu, VCPU_REGS_RCX, svm->tsc_aux);
+
+ skip_emulated_instruction(&svm->vcpu);
+ return 1;
+}
+
static int wbinvd_interception(struct vcpu_svm *svm)
{
kvm_emulate_wbinvd(&svm->vcpu);
@@ -3919,6 +3935,7 @@ static int (*const svm_exit_handlers[])(struct vcpu_svm *svm) = {
[SVM_EXIT_STGI] = stgi_interception,
[SVM_EXIT_CLGI] = clgi_interception,
[SVM_EXIT_SKINIT] = skinit_interception,
+ [SVM_EXIT_RDTSCP] = rdtscp_interception,
[SVM_EXIT_WBINVD] = wbinvd_interception,
[SVM_EXIT_MONITOR] = monitor_interception,
[SVM_EXIT_MWAIT] = mwait_interception,
---
qemu diff:

---
diff --git a/target-i386/cpu.c b/target-i386/cpu.c
index 3bd3cfc3ad16..aa6d0d027d00 100644
--- a/target-i386/cpu.c
+++ b/target-i386/cpu.c
@@ -1332,9 +1332,8 @@ static X86CPUDefinition builtin_x86_defs[] = {
CPUID_DE | CPUID_FP87,
.features[FEAT_1_ECX] =
CPUID_EXT_CX16 | CPUID_EXT_SSE3,
- /* Missing: CPUID_EXT2_RDTSCP */
.features[FEAT_8000_0001_EDX] =
- CPUID_EXT2_LM | CPUID_EXT2_FXSR |
+ CPUID_EXT2_LM | CPUID_EXT2_FXSR | CPUID_EXT2_RDTSCP |
CPUID_EXT2_MMX | CPUID_EXT2_NX | CPUID_EXT2_PSE36 |
CPUID_EXT2_PAT | CPUID_EXT2_CMOV | CPUID_EXT2_MCA |
CPUID_EXT2_PGE | CPUID_EXT2_MTRR | CPUID_EXT2_SYSCALL |
@@ -1362,9 +1361,8 @@ static X86CPUDefinition builtin_x86_defs[] = {
.features[FEAT_1_ECX] =
CPUID_EXT_POPCNT | CPUID_EXT_CX16 | CPUID_EXT_MONITOR |
CPUID_EXT_SSE3,
- /* Missing: CPUID_EXT2_RDTSCP */
.features[FEAT_8000_0001_EDX] =
- CPUID_EXT2_LM | CPUID_EXT2_FXSR |
+ CPUID_EXT2_LM | CPUID_EXT2_FXSR | CPUID_EXT2_RDTSCP |
CPUID_EXT2_MMX | CPUID_EXT2_NX | CPUID_EXT2_PSE36 |
CPUID_EXT2_PAT | CPUID_EXT2_CMOV | CPUID_EXT2_MCA |
CPUID_EXT2_PGE | CPUID_EXT2_MTRR | CPUID_EXT2_SYSCALL |
@@ -1395,9 +1393,8 @@ static X86CPUDefinition builtin_x86_defs[] = {
CPUID_EXT_POPCNT | CPUID_EXT_SSE42 | CPUID_EXT_SSE41 |
CPUID_EXT_CX16 | CPUID_EXT_SSSE3 | CPUID_EXT_PCLMULQDQ |
CPUID_EXT_SSE3,
- /* Missing: CPUID_EXT2_RDTSCP */
.features[FEAT_8000_0001_EDX] =
- CPUID_EXT2_LM |
+ CPUID_EXT2_LM | CPUID_EXT2_RDTSCP |
CPUID_EXT2_PDPE1GB | CPUID_EXT2_FXSR | CPUID_EXT2_MMX |
CPUID_EXT2_NX | CPUID_EXT2_PSE36 | CPUID_EXT2_PAT |
CPUID_EXT2_CMOV | CPUID_EXT2_MCA | CPUID_EXT2_PGE |
@@ -1431,9 +1428,8 @@ static X86CPUDefinition builtin_x86_defs[] = {
CPUID_EXT_AES | CPUID_EXT_POPCNT | CPUID_EXT_SSE42 |
CPUID_EXT_SSE41 | CPUID_EXT_CX16 | CPUID_EXT_FMA |
CPUID_EXT_SSSE3 | CPUID_EXT_PCLMULQDQ | CPUID_EXT_SSE3,
- /* Missing: CPUID_EXT2_RDTSCP */
.features[FEAT_8000_0001_EDX] =
- CPUID_EXT2_LM |
+ CPUID_EXT2_LM | CPUID_EXT2_RDTSCP |
CPUID_EXT2_PDPE1GB | CPUID_EXT2_FXSR | CPUID_EXT2_MMX |
CPUID_EXT2_NX | CPUID_EXT2_PSE36 | CPUID_EXT2_PAT |
CPUID_EXT2_CMOV | CPUID_EXT2_MCA | CPUID_EXT2_PGE |



--
Regards/Gruss,
Boris.

ECO tip #101: Trim your mails when you reply.

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