vmx: Never use physical addresses above 4GB for VMCS state on i386.

Thsi requires special allocation of the vlapic regs page, but does let
us get rid of some top-half writes to a few VMCS fields.

Assert a few more facts about the VMX_BASIC_MSR.

Signed-off-by: Keir Fraser <keir@xensource.com>

diff --git a/xen/arch/x86/hvm/vlapic.c b/xen/arch/x86/hvm/vlapic.c
index 3075ee58a6fc6df500753079cc0f2a22b2d38098..712c7c7523340d8a81d0e3cb3762c104b241d1af 100644 (file)
--- a/xen/arch/x86/hvm/vlapic.c
+++ b/xen/arch/x86/hvm/vlapic.c
@@ -915,10 +915,17 @@ HVM_REGISTER_SAVE_RESTORE(LAPIC_REGS, lapic_save_regs, lapic_load_regs,
 int vlapic_init(struct vcpu *v)
 {
     struct vlapic *vlapic = vcpu_vlapic(v);
+    unsigned int memflags = 0;
 
     HVM_DBG_LOG(DBG_LEVEL_VLAPIC, "%d", v->vcpu_id);
 
-    vlapic->regs_page = alloc_domheap_page(NULL);
+#ifdef __i386__
+    /* 32-bit VMX may be limited to 32-bit physical addresses. */
+    if ( boot_cpu_data.x86_vendor == X86_VENDOR_INTEL )
+        memflags = MEMF_bits(32);
+#endif
+
+    vlapic->regs_page = alloc_domheap_pages(NULL, 0, memflags);
     if ( vlapic->regs_page == NULL )
     {
         dprintk(XENLOG_ERR, "alloc vlapic regs error: %d/%d\n",

diff --git a/xen/arch/x86/hvm/vmx/vmcs.c b/xen/arch/x86/hvm/vmx/vmcs.c
index 06365021855ca7fb25664944c4b813d0ec81e18f..aee5b0e517eff17a43ddb60dafc77d41dbeff129 100644 (file)
--- a/xen/arch/x86/hvm/vmx/vmcs.c
+++ b/xen/arch/x86/hvm/vmx/vmcs.c
@@ -151,6 +151,14 @@ void vmx_init_vmcs_config(void)
 
     /* IA-32 SDM Vol 3B: VMCS size is never greater than 4kB. */
     BUG_ON((vmx_msr_high & 0x1fff) > PAGE_SIZE);
+
+#ifdef __x86_64__
+    /* IA-32 SDM Vol 3B: 64-bit CPUs always have VMX_BASIC_MSR[48]==0. */
+    BUG_ON(vmx_msr_high & (1u<<16));
+#endif
+
+    /* Require Write-Back (WB) memory type for VMCS accesses. */
+    BUG_ON(((vmx_msr_high >> 18) & 15) == 6);
 }
 
 static struct vmcs_struct *vmx_alloc_vmcs(void)
@@ -422,11 +430,8 @@ static void construct_vmcs(struct vcpu *v)
 
     if ( cpu_has_vmx_tpr_shadow )
     {
-        paddr_t virt_page_ma = page_to_maddr(vcpu_vlapic(v)->regs_page);
-        __vmwrite(VIRTUAL_APIC_PAGE_ADDR, virt_page_ma);
-#if defined (CONFIG_X86_PAE)
-        __vmwrite(VIRTUAL_APIC_PAGE_ADDR_HIGH, virt_page_ma >> 32);
-#endif
+        __vmwrite(VIRTUAL_APIC_PAGE_ADDR,
+                  page_to_maddr(vcpu_vlapic(v)->regs_page));
         __vmwrite(TPR_THRESHOLD, 0);
     }
 

diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
index b9e3825377c6d1fb43bc56aea186a298ce304534..dbe95771034096b90d94b55072b27c91ee31d647 100644 (file)
--- a/xen/arch/x86/hvm/vmx/vmx.c
+++ b/xen/arch/x86/hvm/vmx/vmx.c
@@ -2718,7 +2718,7 @@ static void vmx_free_vlapic_mapping(struct domain *d)
 
 static void vmx_install_vlapic_mapping(struct vcpu *v)
 {
-    paddr_t virt_page_ma, apic_page_ma;
+    unsigned long virt_page_ma, apic_page_ma;
 
     if ( !cpu_has_vmx_virtualize_apic_accesses )
         return;
@@ -2730,10 +2730,6 @@ static void vmx_install_vlapic_mapping(struct vcpu *v)
     vmx_vmcs_enter(v);
     __vmwrite(VIRTUAL_APIC_PAGE_ADDR, virt_page_ma);
     __vmwrite(APIC_ACCESS_ADDR, apic_page_ma);
-#if defined (CONFIG_X86_PAE)
-    __vmwrite(VIRTUAL_APIC_PAGE_ADDR_HIGH, virt_page_ma >> 32);
-    __vmwrite(APIC_ACCESS_ADDR_HIGH, apic_page_ma >> 32);
-#endif
     vmx_vmcs_exit(v);
 }