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Re: [Xen-devel] [PATCH RFC v12 08/21] pvh: vmx-specific changes



On 13/09/13 17:25, George Dunlap wrote:
Changes:
* Enforce HAP mode for now
* Disable exits related to virtual interrupts or emulated APICs
* Disable changing paging mode
  - "unrestricted guest" (i.e., real mode for EPT) disabled
  - write guest EFER disabled
* Start in 64-bit mode
* Force TSC mode to be "none"
* Paging mode update to happen in arch_set_info_guest

Signed-off-by: George Dunlap <george.dunlap@xxxxxxxxxxxxx>
Signed-off-by: Mukesh Rathor <mukesh.rathor@xxxxxxxxxx>
CC: Jan Beulich <jan.beulich@xxxxxxxx>
CC: Tim Deegan <tim@xxxxxxx>
CC: Keir Fraser <keir@xxxxxxx>
---
  xen/arch/x86/hvm/vmx/vmcs.c |  140 +++++++++++++++++++++++++++++++++++++++++--
  1 file changed, 135 insertions(+), 5 deletions(-)

diff --git a/xen/arch/x86/hvm/vmx/vmcs.c b/xen/arch/x86/hvm/vmx/vmcs.c
index fa90493..f016343 100644
--- a/xen/arch/x86/hvm/vmx/vmcs.c
+++ b/xen/arch/x86/hvm/vmx/vmcs.c
@@ -828,6 +828,58 @@ void virtual_vmcs_vmwrite(void *vvmcs, u32 vmcs_encoding, 
u64 val)
      virtual_vmcs_exit(vvmcs);
  }
+static int pvh_check_requirements(struct vcpu *v)
+{
+    u64 required, tmpval = real_cr4_to_pv_guest_cr4(mmu_cr4_features);
+
+    if ( !paging_mode_hap(v->domain) )
+    {
+        printk(XENLOG_G_INFO "HAP is required for PVH guest.\n");
+        return -EINVAL;
+    }
+    if ( !cpu_has_vmx_ept )
+    {
+        printk(XENLOG_G_INFO "PVH: CPU does not have EPT support\n");
+        return -ENOSYS;
+    }
+    if ( !cpu_has_vmx_pat )
+    {
+        printk(XENLOG_G_INFO "PVH: CPU does not have PAT support\n");
+        return -ENOSYS;
+    }
+    if ( !cpu_has_vmx_msr_bitmap )
+    {
+        printk(XENLOG_G_INFO "PVH: CPU does not have msr bitmap\n");
+        return -ENOSYS;
+    }
+    if ( !cpu_has_vmx_secondary_exec_control )
+    {
+        printk(XENLOG_G_INFO "CPU Secondary exec is required to run PVH\n");
+        return -ENOSYS;
+    }
+
+    /*
+     * If rdtsc exiting is turned on and it goes thru emulate_privileged_op,
+     * then pv_vcpu.ctrlreg must be added to the pvh struct.
+     */
+    if ( v->domain->arch.vtsc )
+    {
+        printk(XENLOG_G_INFO
+               "At present PVH only supports the default timer mode\n");
+        return -ENOSYS;
+    }
+
+    required = X86_CR4_PAE | X86_CR4_VMXE | X86_CR4_OSFXSR;
+    if ( (tmpval & required) != required )
+    {
+        printk(XENLOG_G_INFO "PVH: required CR4 features not available:%lx\n",
+               required);
+        return -ENOSYS;
+    }
+
+    return 0;
+}
+
  static int construct_vmcs(struct vcpu *v)
  {
      struct domain *d = v->domain;
@@ -836,6 +888,13 @@ static int construct_vmcs(struct vcpu *v)
      u32 vmexit_ctl = vmx_vmexit_control;
      u32 vmentry_ctl = vmx_vmentry_control;
+ if ( is_pvh_domain(d) )
+    {
+        int rc = pvh_check_requirements(v);
+        if ( rc )
+            return rc;
+    }
+
      vmx_vmcs_enter(v);
/* VMCS controls. */
@@ -874,7 +933,44 @@ static int construct_vmcs(struct vcpu *v)
      /* Do not enable Monitor Trap Flag unless start single step debug */
      v->arch.hvm_vmx.exec_control &= ~CPU_BASED_MONITOR_TRAP_FLAG;
+ if ( is_pvh_domain(d) )
+    {
+        /* Disable virtual apics, TPR */
+        v->arch.hvm_vmx.secondary_exec_control &=
+            ~(SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES
+              | SECONDARY_EXEC_APIC_REGISTER_VIRT
+              | SECONDARY_EXEC_VIRTUAL_INTR_DELIVERY);
+        v->arch.hvm_vmx.exec_control &= ~CPU_BASED_TPR_SHADOW;
+
+        /* Disable wbinvd (only necessary for MMIO),
+         * unrestricted guest (real mode for EPT) */
+        v->arch.hvm_vmx.secondary_exec_control &=
+            ~(SECONDARY_EXEC_UNRESTRICTED_GUEST
+              | SECONDARY_EXEC_WBINVD_EXITING);
+
+        ASSERT(v->arch.hvm_vmx.exec_control & 
CPU_BASED_ACTIVATE_SECONDARY_CONTROLS);
+        ASSERT(v->arch.hvm_vmx.exec_control & CPU_BASED_ACTIVATE_MSR_BITMAP);
+        ASSERT(!(v->arch.hvm_vmx.exec_control & CPU_BASED_RDTSC_EXITING));
+
+        /*
+         * Note: we run with default VM_ENTRY_LOAD_DEBUG_CTLS of 1, which means
+         * upon vmentry, the cpu reads/loads VMCS.DR7 and VMCS.DEBUGCTLS, and 
not
+         * use the host values. 0 would cause it to not use the VMCS values.
+         */
+
+        /* PVH: I don't think these are necessary */
+        v->arch.hvm_vmx.exec_control &= ~CPU_BASED_VIRTUAL_NMI_PENDING;
+        vmentry_ctl &= ~VM_ENTRY_LOAD_GUEST_EFER;
+        vmentry_ctl &= ~VM_ENTRY_SMM;
+        vmentry_ctl &= ~VM_ENTRY_DEACT_DUAL_MONITOR;

Mukesh, I couldn't figure out why you had set these. What are these about, and are they really necessary?

+    /* PVH: Why is ET not set? */
+    v->arch.hvm_vcpu.guest_cr[0] = is_pvh_domain(d) ?
+        ( X86_CR0_PG | X86_CR0_NE | X86_CR0_PE | X86_CR0_WP )
+        : ( X86_CR0_PE | X86_CR0_ET );

I also couldn't figure out why CR0_ET wasn't set for PVH vms; is it not set for PV vms?

 -George

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