[Xen-devel] [PATCH RFC 06/12] x86/vvmx: add stale_eptp flag

[Sergey Dyasli <sergey.dyasli@xxxxxxxxxx>]

The new variable will indicate if update of a shadow EPTP is needed
prior to vmentry. Update is required if a nested vcpu gets a new np2m
or if its np2m was flushed by an IPI.

Helper function nvcpu_flush() is added.

Signed-off-by: Sergey Dyasli <sergey.dyasli@xxxxxxxxxx>
---
 xen/arch/x86/hvm/nestedhvm.c       |  1 +
 xen/arch/x86/hvm/vmx/entry.S       |  6 ++++++
 xen/arch/x86/hvm/vmx/vmx.c         |  8 +++++++-
 xen/arch/x86/hvm/vmx/vvmx.c        | 15 +++++++++++++++
 xen/arch/x86/mm/p2m.c              | 10 ++++++++--
 xen/include/asm-x86/hvm/vmx/vvmx.h |  2 ++
 6 files changed, 39 insertions(+), 3 deletions(-)

diff --git a/xen/arch/x86/hvm/nestedhvm.c b/xen/arch/x86/hvm/nestedhvm.c
index 32b8acca6a..e9b1d8e628 100644
--- a/xen/arch/x86/hvm/nestedhvm.c
+++ b/xen/arch/x86/hvm/nestedhvm.c
@@ -108,6 +108,7 @@ nestedhvm_flushtlb_ipi(void *info)
      */
     hvm_asid_flush_core();
     vcpu_nestedhvm(v).nv_p2m = NULL;
+    vcpu_2_nvmx(v).stale_eptp = true;
 }
 
 void
diff --git a/xen/arch/x86/hvm/vmx/entry.S b/xen/arch/x86/hvm/vmx/entry.S
index 9f1755b31c..5480206cac 100644
--- a/xen/arch/x86/hvm/vmx/entry.S
+++ b/xen/arch/x86/hvm/vmx/entry.S
@@ -77,6 +77,8 @@ UNLIKELY_END(realmode)
 
         mov  %rsp,%rdi
         call vmx_vmenter_helper
+        cmp  $0,%eax
+        jne .Lvmx_vmentry_restart
         mov  VCPU_hvm_guest_cr2(%rbx),%rax
 
         pop  %r15
@@ -115,6 +117,10 @@ ENTRY(vmx_asm_do_vmentry)
         GET_CURRENT(bx)
         jmp  .Lvmx_do_vmentry
 
+.Lvmx_vmentry_restart:
+        sti
+        jmp  .Lvmx_do_vmentry
+
 .Lvmx_goto_emulator:
         sti
         mov  %rsp,%rdi
diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
index 69ce3aae25..35aa57e24f 100644
--- a/xen/arch/x86/hvm/vmx/vmx.c
+++ b/xen/arch/x86/hvm/vmx/vmx.c
@@ -4236,13 +4236,17 @@ static void lbr_fixup(void)
         bdw_erratum_bdf14_fixup();
 }
 
-void vmx_vmenter_helper(const struct cpu_user_regs *regs)
+int vmx_vmenter_helper(const struct cpu_user_regs *regs)
 {
     struct vcpu *curr = current;
     u32 new_asid, old_asid;
     struct hvm_vcpu_asid *p_asid;
     bool_t need_flush;
 
+    /* Shadow EPTP can't be updated here because irqs are disabled */
+     if ( nestedhvm_vcpu_in_guestmode(curr) && vcpu_2_nvmx(curr).stale_eptp )
+         return 1;
+
     if ( curr->domain->arch.hvm_domain.pi_ops.do_resume )
         curr->domain->arch.hvm_domain.pi_ops.do_resume(curr);
 
@@ -4303,6 +4307,8 @@ void vmx_vmenter_helper(const struct cpu_user_regs *regs)
     __vmwrite(GUEST_RIP,    regs->rip);
     __vmwrite(GUEST_RSP,    regs->rsp);
     __vmwrite(GUEST_RFLAGS, regs->rflags | X86_EFLAGS_MBS);
+
+    return 0;
 }
 
 /*
diff --git a/xen/arch/x86/hvm/vmx/vvmx.c b/xen/arch/x86/hvm/vmx/vvmx.c
index 1011829c15..7b193767cd 100644
--- a/xen/arch/x86/hvm/vmx/vvmx.c
+++ b/xen/arch/x86/hvm/vmx/vvmx.c
@@ -120,6 +120,7 @@ int nvmx_vcpu_initialise(struct vcpu *v)
     nvmx->iobitmap[1] = NULL;
     nvmx->msrbitmap = NULL;
     INIT_LIST_HEAD(&nvmx->launched_list);
+    nvmx->stale_eptp = false;
     return 0;
 }
  
@@ -1390,12 +1391,26 @@ static void virtual_vmexit(struct cpu_user_regs *regs)
     vmsucceed(regs);
 }
 
+static void nvmx_eptp_update(void)
+{
+    if ( !nestedhvm_vcpu_in_guestmode(current) ||
+          vcpu_nestedhvm(current).nv_vmexit_pending ||
+         !vcpu_2_nvmx(current).stale_eptp ||
+         !nestedhvm_paging_mode_hap(current) )
+        return;
+
+    __vmwrite(EPT_POINTER, get_shadow_eptp(current));
+    vcpu_2_nvmx(current).stale_eptp = false;
+}
+
 void nvmx_switch_guest(void)
 {
     struct vcpu *v = current;
     struct nestedvcpu *nvcpu = &vcpu_nestedhvm(v);
     struct cpu_user_regs *regs = guest_cpu_user_regs();
 
+    nvmx_eptp_update();
+
     /*
      * A pending IO emulation may still be not finished. In this case, no
      * virtual vmswitch is allowed. Or else, the following IO emulation will
diff --git a/xen/arch/x86/mm/p2m.c b/xen/arch/x86/mm/p2m.c
index 4fc2d94b46..3d65899b05 100644
--- a/xen/arch/x86/mm/p2m.c
+++ b/xen/arch/x86/mm/p2m.c
@@ -1817,6 +1817,12 @@ static void assign_np2m(struct vcpu *v, struct 
p2m_domain *p2m)
     cpumask_set_cpu(v->processor, p2m->dirty_cpumask);
 }
 
+static void nvcpu_flush(struct vcpu *v)
+{
+    hvm_asid_flush_vcpu(v);
+    vcpu_2_nvmx(v).stale_eptp = true;
+}
+
 struct p2m_domain *
 p2m_get_nestedp2m(struct vcpu *v)
 {
@@ -1840,7 +1846,7 @@ p2m_get_nestedp2m(struct vcpu *v)
         if ( p2m->np2m_base == np2m_base || p2m->np2m_base == P2M_BASE_EADDR )
         {
             if ( p2m->np2m_base == P2M_BASE_EADDR )
-                hvm_asid_flush_vcpu(v);
+                nvcpu_flush(v);
             p2m->np2m_base = np2m_base;
             assign_np2m(v, p2m);
             p2m_unlock(p2m);
@@ -1857,7 +1863,7 @@ p2m_get_nestedp2m(struct vcpu *v)
     p2m_flush_table(p2m);
     p2m_lock(p2m);
     p2m->np2m_base = np2m_base;
-    hvm_asid_flush_vcpu(v);
+    nvcpu_flush(v);
     assign_np2m(v, p2m);
     p2m_unlock(p2m);
     nestedp2m_unlock(d);
diff --git a/xen/include/asm-x86/hvm/vmx/vvmx.h 
b/xen/include/asm-x86/hvm/vmx/vvmx.h
index 3285b03bbb..ddc2569f64 100644
--- a/xen/include/asm-x86/hvm/vmx/vvmx.h
+++ b/xen/include/asm-x86/hvm/vmx/vvmx.h
@@ -51,6 +51,8 @@ struct nestedvmx {
     } ept;
     uint32_t guest_vpid;
     struct list_head launched_list;
+
+    bool stale_eptp; /* True, when EPTP in the shadow VMCS is no longer valid 
*/
 };
 
 #define vcpu_2_nvmx(v) (vcpu_nestedhvm(v).u.nvmx)
-- 
2.11.0


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