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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-changelog] [xen staging] x86/hvm: Corrections to RDTSCP intercept handling
commit 3fd3fda9c26fc3c4f77250f795ed7ff9d38e2ec6
Author: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
AuthorDate: Fri Nov 30 16:14:08 2018 +0000
Commit: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
CommitDate: Mon Dec 17 16:28:03 2018 +0000
x86/hvm: Corrections to RDTSCP intercept handling
For both VT-x and SVM, the RDTSCP intercept will trigger if the pipeline
supports the instruction, but the guest may not have RDTSCP in its
featureset.
Bring the vmexit handlers in line with the main emulator behaviour by
optionally handing back #UD.
Next on the AMD side, if RDTSCP actually ends up being intercepted on a
debug
build or first-gen SVM hardware which lacks NRIP, we first update regs->rcx,
then call __get_instruction_length() asking for RDTSC. As the two
instructions are different (and indeed, different lengths!),
__get_instruction_length_from_list() fails and hands back a #GP fault.
This can demonstrated by putting a guest into tsc_mode="always emulate" and
executing an RDTSCP instruction:
(d1) --- Xen Test Framework ---
(d1) Environment: HVM 64bit (Long mode 4 levels)
(d1) Test rdtscp
(d1) TSC mode 1
(XEN) emulate.c:147:d1v0 __get_instruction_length: Mismatch between
expected and actual instruction:
(XEN) emulate.c:152:d1v0 insn_index 8, opcode 0xf0031 modrm 0
(XEN) emulate.c:154:d1v0 rip 0x10475f, nextrip 0x104762, len 3
(XEN) SVM insn len emulation failed (1): d1v0 64bit @ 0008:0010475f -> 0f
01 f9 0f 31 5b 31 ff 31 c0 e9 c2 db ff ff 00
(d1) ******************************
(d1) PANIC: Unhandled exception at 0008:000000000010475f
(d1) Vec 13 #GP[0000]
(d1) ******************************
First, teach __get_instruction_length() to cope with RDTSCP, and improve
svm_vmexit_do_rdtsc() to ask for the correct instruction. Move the
regs->rcx
adjustment into this function to ensure it gets done after we are done
potentially raising faults.
Reported-by: Paul Durrant <paul.durrant@xxxxxxxxxx>
Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Reviewed-by: Brian Woods <brian.woods@xxxxxxx>
Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>
Reviewed-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
---
xen/arch/x86/hvm/svm/emulate.c | 1 +
xen/arch/x86/hvm/svm/svm.c | 22 +++++++++++++++++-----
xen/arch/x86/hvm/vmx/vmx.c | 8 ++++++++
xen/include/asm-x86/hvm/svm/emulate.h | 1 +
4 files changed, 27 insertions(+), 5 deletions(-)
diff --git a/xen/arch/x86/hvm/svm/emulate.c b/xen/arch/x86/hvm/svm/emulate.c
index 3d04af0ea9..4abeab8655 100644
--- a/xen/arch/x86/hvm/svm/emulate.c
+++ b/xen/arch/x86/hvm/svm/emulate.c
@@ -75,6 +75,7 @@ static const struct {
[INSTR_STGI] = { X86EMUL_OPC(0x0f, 0x01), MODRM(3, 3, 4) },
[INSTR_CLGI] = { X86EMUL_OPC(0x0f, 0x01), MODRM(3, 3, 5) },
[INSTR_INVLPGA] = { X86EMUL_OPC(0x0f, 0x01), MODRM(3, 3, 7) },
+ [INSTR_RDTSCP] = { X86EMUL_OPC(0x0f, 0x01), MODRM(3, 7, 1) },
[INSTR_INVD] = { X86EMUL_OPC(0x0f, 0x08) },
[INSTR_WBINVD] = { X86EMUL_OPC(0x0f, 0x09) },
[INSTR_WRMSR] = { X86EMUL_OPC(0x0f, 0x30) },
diff --git a/xen/arch/x86/hvm/svm/svm.c b/xen/arch/x86/hvm/svm/svm.c
index 40937bfa47..9464394b0d 100644
--- a/xen/arch/x86/hvm/svm/svm.c
+++ b/xen/arch/x86/hvm/svm/svm.c
@@ -2279,14 +2279,28 @@ static void svm_vmexit_do_hlt(struct vmcb_struct *vmcb,
hvm_hlt(regs->eflags);
}
-static void svm_vmexit_do_rdtsc(struct cpu_user_regs *regs)
+static void svm_vmexit_do_rdtsc(struct cpu_user_regs *regs, bool rdtscp)
{
+ struct vcpu *curr = current;
+ const struct domain *currd = curr->domain;
+ enum instruction_index insn = rdtscp ? INSTR_RDTSCP : INSTR_RDTSC;
unsigned int inst_len;
- if ( (inst_len = __get_instruction_length(current, INSTR_RDTSC)) == 0 )
+ if ( rdtscp && !currd->arch.cpuid->extd.rdtscp &&
+ currd->arch.tsc_mode != TSC_MODE_PVRDTSCP )
+ {
+ hvm_inject_hw_exception(TRAP_invalid_op, X86_EVENT_NO_EC);
return;
+ }
+
+ if ( (inst_len = __get_instruction_length(curr, insn)) == 0 )
+ return;
+
__update_guest_eip(regs, inst_len);
+ if ( rdtscp )
+ regs->rcx = hvm_msr_tsc_aux(curr);
+
hvm_rdtsc_intercept(regs);
}
@@ -2968,10 +2982,8 @@ void svm_vmexit_handler(struct cpu_user_regs *regs)
break;
case VMEXIT_RDTSCP:
- regs->rcx = hvm_msr_tsc_aux(v);
- /* fall through */
case VMEXIT_RDTSC:
- svm_vmexit_do_rdtsc(regs);
+ svm_vmexit_do_rdtsc(regs, exit_reason == VMEXIT_RDTSCP);
break;
case VMEXIT_MONITOR:
diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
index 7f77d1fd28..2166b0dfe4 100644
--- a/xen/arch/x86/hvm/vmx/vmx.c
+++ b/xen/arch/x86/hvm/vmx/vmx.c
@@ -3589,6 +3589,7 @@ void vmx_vmexit_handler(struct cpu_user_regs *regs)
unsigned long exit_qualification, exit_reason, idtv_info, intr_info = 0;
unsigned int vector = 0, mode;
struct vcpu *v = current;
+ struct domain *currd = v->domain;
__vmread(GUEST_RIP, ®s->rip);
__vmread(GUEST_RSP, ®s->rsp);
@@ -3956,6 +3957,13 @@ void vmx_vmexit_handler(struct cpu_user_regs *regs)
vmx_invlpg_intercept(exit_qualification);
break;
case EXIT_REASON_RDTSCP:
+ if ( !currd->arch.cpuid->extd.rdtscp &&
+ currd->arch.tsc_mode != TSC_MODE_PVRDTSCP )
+ {
+ hvm_inject_hw_exception(TRAP_invalid_op, X86_EVENT_NO_EC);
+ break;
+ }
+
regs->rcx = hvm_msr_tsc_aux(v);
/* fall through */
case EXIT_REASON_RDTSC:
diff --git a/xen/include/asm-x86/hvm/svm/emulate.h
b/xen/include/asm-x86/hvm/svm/emulate.h
index 3de8236301..ca92abbe28 100644
--- a/xen/include/asm-x86/hvm/svm/emulate.h
+++ b/xen/include/asm-x86/hvm/svm/emulate.h
@@ -30,6 +30,7 @@ enum instruction_index {
INSTR_HLT,
INSTR_INT3,
INSTR_RDTSC,
+ INSTR_RDTSCP,
INSTR_PAUSE,
INSTR_XSETBV,
INSTR_VMRUN,
--
generated by git-patchbot for /home/xen/git/xen.git#staging
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