[Xen-devel] [PATCH v14 07/17] pvh: vmx-specific changes

[George Dunlap <george.dunlap@xxxxxxxxxxxxx>]

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>
---
v14:
 - Mask out bits of cr4 that the guest is not allowed to set
v13:
 - Fix up default cr0 settings
 - Get rid of some unnecessary PVH-related changes
 - Return EOPNOTSUPP instead of ENOSYS if hardware features are not present
 - Remove an unnecessary variable from pvh_check_requirements
CC: Jan Beulich <jbeulich@xxxxxxxx>
CC: Tim Deegan <tim@xxxxxxx>
CC: Keir Fraser <keir@xxxxxxx>
---
 xen/arch/x86/hvm/vmx/vmcs.c |  132 +++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 128 insertions(+), 4 deletions(-)

diff --git a/xen/arch/x86/hvm/vmx/vmcs.c b/xen/arch/x86/hvm/vmx/vmcs.c
index f2a2857..ba05ebb 100644
--- a/xen/arch/x86/hvm/vmx/vmcs.c
+++ b/xen/arch/x86/hvm/vmx/vmcs.c
@@ -28,6 +28,7 @@
 #include <asm/msr.h>
 #include <asm/xstate.h>
 #include <asm/hvm/hvm.h>
+#include <asm/hvm/nestedhvm.h>
 #include <asm/hvm/io.h>
 #include <asm/hvm/support.h>
 #include <asm/hvm/vmx/vmx.h>
@@ -841,6 +842,60 @@ 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;
+
+    /* Check for required hardware features */
+    if ( !cpu_has_vmx_ept )
+    {
+        printk(XENLOG_G_INFO "PVH: CPU does not have EPT support\n");
+        return -EOPNOTSUPP;
+    }
+    if ( !cpu_has_vmx_pat )
+    {
+        printk(XENLOG_G_INFO "PVH: CPU does not have PAT support\n");
+        return -EOPNOTSUPP;
+    }
+    if ( !cpu_has_vmx_msr_bitmap )
+    {
+        printk(XENLOG_G_INFO "PVH: CPU does not have msr bitmap\n");
+        return -EOPNOTSUPP;
+    }
+    if ( !cpu_has_vmx_secondary_exec_control )
+    {
+        printk(XENLOG_G_INFO "CPU Secondary exec is required to run PVH\n");
+        return -EOPNOTSUPP;
+    }
+    required = X86_CR4_PAE | X86_CR4_VMXE | X86_CR4_OSFXSR;
+    if ( (real_cr4_to_pv_guest_cr4(mmu_cr4_features) & required) != required )
+    {
+        printk(XENLOG_G_INFO "PVH: required CR4 features not available:%lx\n",
+               required);
+        return -EOPNOTSUPP;
+    }
+
+    /* Check for required configuration options */
+    if ( !paging_mode_hap(v->domain) )
+    {
+        printk(XENLOG_G_INFO "HAP is required for PVH guest.\n");
+        return -EINVAL;
+    }
+    /*
+     * 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 -EINVAL;
+    }
+
+
+    return 0;
+}
+
 static int construct_vmcs(struct vcpu *v)
 {
     struct domain *d = v->domain;
@@ -849,6 +904,13 @@ 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. */
@@ -887,7 +949,32 @@ 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);
+
+        /* Start in 64-bit mode.
+         * PVH 32bitfixme. */
+        vmentry_ctl |= VM_ENTRY_IA32E_MODE;       /* GUEST_EFER.LME/LMA 
ignored */
+
+        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));
+    }
+
     vmx_update_cpu_exec_control(v);
+
     __vmwrite(VM_EXIT_CONTROLS, vmexit_ctl);
     __vmwrite(VM_ENTRY_CONTROLS, vmentry_ctl);
 
@@ -923,6 +1010,17 @@ static int construct_vmcs(struct vcpu *v)
         vmx_disable_intercept_for_msr(v, MSR_IA32_SYSENTER_EIP, MSR_TYPE_R | 
MSR_TYPE_W);
         if ( cpu_has_vmx_pat && paging_mode_hap(d) )
             vmx_disable_intercept_for_msr(v, MSR_IA32_CR_PAT, MSR_TYPE_R | 
MSR_TYPE_W);
+        if ( is_pvh_domain(d) )
+            vmx_disable_intercept_for_msr(v, MSR_SHADOW_GS_BASE, MSR_TYPE_R | 
MSR_TYPE_W);
+
+        /*
+         * PVH: We don't disable intercepts for MSRs: MSR_STAR, MSR_LSTAR,
+         *      MSR_CSTAR, and MSR_SYSCALL_MASK because we need to specify
+         *      save/restore area to save/restore at every VM exit and entry.
+         *      Instead, let the intercept functions save them into
+         *      vmx_msr_state fields. See comment in vmx_restore_host_msrs().
+         *      See also vmx_restore_guest_msrs().
+         */
     }
 
     /* I/O access bitmap. */
@@ -1011,7 +1109,11 @@ static int construct_vmcs(struct vcpu *v)
     __vmwrite(GUEST_DS_AR_BYTES, 0xc093);
     __vmwrite(GUEST_FS_AR_BYTES, 0xc093);
     __vmwrite(GUEST_GS_AR_BYTES, 0xc093);
-    __vmwrite(GUEST_CS_AR_BYTES, 0xc09b); /* exec/read, accessed */
+    if ( is_pvh_domain(d) )
+        /* CS.L == 1, exec, read/write, accessed. PVH 32bitfixme. */
+        __vmwrite(GUEST_CS_AR_BYTES, 0xa09b);
+    else
+        __vmwrite(GUEST_CS_AR_BYTES, 0xc09b); /* exec/read, accessed */
 
     /* Guest IDT. */
     __vmwrite(GUEST_IDTR_BASE, 0);
@@ -1041,12 +1143,29 @@ static int construct_vmcs(struct vcpu *v)
               | (1U << TRAP_no_device);
     vmx_update_exception_bitmap(v);
 
+    /* In HVM domains, this happens on the realmode->paging
+     * transition.  Since PVH never goes through this transition, we
+     * need to do it at start-of-day. */
+    if ( is_pvh_domain(d) )
+        vmx_update_debug_state(v);
+
     v->arch.hvm_vcpu.guest_cr[0] = X86_CR0_PE | X86_CR0_ET;
+
+    /* PVH domains always start in paging mode */
+    if ( is_pvh_domain(d) )
+        v->arch.hvm_vcpu.guest_cr[0] |= X86_CR0_PG | X86_CR0_NE | X86_CR0_WP;
+
     hvm_update_guest_cr(v, 0);
 
-    v->arch.hvm_vcpu.guest_cr[4] = 0;
+    v->arch.hvm_vcpu.guest_cr[4] = is_pvh_domain(d) ?
+        (real_cr4_to_pv_guest_cr4(mmu_cr4_features) 
+         & ~HVM_CR4_GUEST_RESERVED_BITS(v))
+        : 0;
     hvm_update_guest_cr(v, 4);
 
+    if ( is_pvh_domain(d) )
+        v->arch.hvm_vmx.vmx_realmode = 0;
+
     if ( cpu_has_vmx_tpr_shadow )
     {
         __vmwrite(VIRTUAL_APIC_PAGE_ADDR,
@@ -1076,9 +1195,14 @@ static int construct_vmcs(struct vcpu *v)
 
     vmx_vmcs_exit(v);
 
-    paging_update_paging_modes(v); /* will update HOST & GUEST_CR3 as reqd */
+    /* PVH: paging mode is updated by arch_set_info_guest(). */
+    if ( is_hvm_vcpu(v) )
+    {
+        /* will update HOST & GUEST_CR3 as reqd */
+        paging_update_paging_modes(v);
 
-    vmx_vlapic_msr_changed(v);
+        vmx_vlapic_msr_changed(v);
+    }
 
     return 0;
 }
-- 
1.7.9.5


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