[Xen-devel] [PATCH RFC 5/9] xen: Support for VMCALL mem_events

[Razvan Cojocaru <rcojocaru@xxxxxxxxxxxxxxx>]

Added support for VMCALL events (the memory introspection library
will have the guest trigger VMCALLs, which will then be sent along
via the mem_event mechanism).

Signed-off-by: Razvan Cojocaru <rcojocaru@xxxxxxxxxxxxxxx>
---
 xen/arch/x86/hvm/hvm.c          |    8 ++++++++
 xen/arch/x86/hvm/vmx/vmx.c      |   15 ++++++++++++++-
 xen/include/asm-x86/hvm/hvm.h   |    1 +
 xen/include/public/hvm/params.h |    4 +++-
 xen/include/public/mem_event.h  |    1 +
 5 files changed, 27 insertions(+), 2 deletions(-)

diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index f65a5f5..df696d1 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -6130,6 +6130,14 @@ void hvm_memory_event_msr(unsigned long msr, unsigned 
long value)
                            value, ~value, 1, msr);
 }
 
+void hvm_memory_event_vmcall(unsigned long rip, unsigned long eax)
+{
+    hvm_memory_event_traps(current->domain->arch.hvm_domain
+                             .params[HVM_PARAM_MEMORY_EVENT_VMCALL],
+                           MEM_EVENT_REASON_VMCALL,
+                           rip, ~rip, 1, eax);
+}
+
 int hvm_memory_event_int3(unsigned long gla) 
 {
     uint32_t pfec = PFEC_page_present;
diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
index fed21b6..b4c12cd 100644
--- a/xen/arch/x86/hvm/vmx/vmx.c
+++ b/xen/arch/x86/hvm/vmx/vmx.c
@@ -2880,8 +2880,21 @@ void vmx_vmexit_handler(struct cpu_user_regs *regs)
     case EXIT_REASON_VMCALL:
     {
         int rc;
+        unsigned long eax = regs->eax;
+
         HVMTRACE_1D(VMMCALL, regs->eax);
-        rc = hvm_do_hypercall(regs);
+
+        if ( regs->eax != 0x494e5452 ) /* Introcore magic */
+        {
+            rc = hvm_do_hypercall(regs);
+        }
+        else
+        {
+            hvm_memory_event_vmcall(guest_cpu_user_regs()->eip, eax);
+            update_guest_eip();
+            break;
+        }
+
         if ( rc != HVM_HCALL_preempted )
         {
             update_guest_eip(); /* Safe: VMCALL */
diff --git a/xen/include/asm-x86/hvm/hvm.h b/xen/include/asm-x86/hvm/hvm.h
index 90e69f5..67e365b 100644
--- a/xen/include/asm-x86/hvm/hvm.h
+++ b/xen/include/asm-x86/hvm/hvm.h
@@ -532,6 +532,7 @@ void hvm_memory_event_cr0(unsigned long value, unsigned 
long old);
 void hvm_memory_event_cr3(unsigned long value, unsigned long old);
 void hvm_memory_event_cr4(unsigned long value, unsigned long old);
 void hvm_memory_event_msr(unsigned long msr, unsigned long value);
+void hvm_memory_event_vmcall(unsigned long rip, unsigned long eax);
 /* Called for current VCPU on int3: returns -1 if no listener */
 int hvm_memory_event_int3(unsigned long gla);
 
diff --git a/xen/include/public/hvm/params.h b/xen/include/public/hvm/params.h
index f830bdd..ea2eee6 100644
--- a/xen/include/public/hvm/params.h
+++ b/xen/include/public/hvm/params.h
@@ -148,6 +148,8 @@
 #define HVM_PARAM_IOREQ_SERVER_PFN 32
 #define HVM_PARAM_NR_IOREQ_SERVER_PAGES 33
 
-#define HVM_NR_PARAMS          34
+#define HVM_PARAM_MEMORY_EVENT_VMCALL 34
+
+#define HVM_NR_PARAMS          35
 
 #endif /* __XEN_PUBLIC_HVM_PARAMS_H__ */
diff --git a/xen/include/public/mem_event.h b/xen/include/public/mem_event.h
index 24ac67d..5fa2858 100644
--- a/xen/include/public/mem_event.h
+++ b/xen/include/public/mem_event.h
@@ -47,6 +47,7 @@
 #define MEM_EVENT_REASON_SINGLESTEP  6    /* single step was invoked: gla/gfn 
are RIP */
 #define MEM_EVENT_REASON_MSR         7    /* MSR was hit: gfn is MSR value, 
gla is MSR address;
                                              does NOT honour 
HVMPME_onchangeonly */
+#define MEM_EVENT_REASON_VMCALL      8    /* VMCALL: gfn is RIP, gla is EAX */
 
 typedef struct mem_event_regs_st {
     uint64_t rax;
-- 
1.7.9.5


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