[Xen-changelog] [xen-unstable] vmx: Never use physical addresses above 4GB for VMCS state on i386.

[Xen patchbot-unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User kfraser@xxxxxxxxxxxxxxxxxxxxx
# Date 1184107062 -3600
# Node ID 25a42f826a630f2e9ff19a73005051ae2e92b96c
# Parent  1315b0901deaedcc375e1ec3cb97a67d7c1804be
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@xxxxxxxxxxxxx>
---
 xen/arch/x86/hvm/vlapic.c   |    9 ++++++++-
 xen/arch/x86/hvm/vmx/vmcs.c |   15 ++++++++++-----
 xen/arch/x86/hvm/vmx/vmx.c  |    6 +-----
 3 files changed, 19 insertions(+), 11 deletions(-)

diff -r 1315b0901dea -r 25a42f826a63 xen/arch/x86/hvm/vlapic.c
--- a/xen/arch/x86/hvm/vlapic.c Tue Jul 10 15:45:44 2007 +0100
+++ b/xen/arch/x86/hvm/vlapic.c Tue Jul 10 23:37:42 2007 +0100
@@ -915,10 +915,17 @@ int vlapic_init(struct vcpu *v)
 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 -r 1315b0901dea -r 25a42f826a63 xen/arch/x86/hvm/vmx/vmcs.c
--- a/xen/arch/x86/hvm/vmx/vmcs.c       Tue Jul 10 15:45:44 2007 +0100
+++ b/xen/arch/x86/hvm/vmx/vmcs.c       Tue Jul 10 23:37:42 2007 +0100
@@ -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 *
 
     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 -r 1315b0901dea -r 25a42f826a63 xen/arch/x86/hvm/vmx/vmx.c
--- a/xen/arch/x86/hvm/vmx/vmx.c        Tue Jul 10 15:45:44 2007 +0100
+++ b/xen/arch/x86/hvm/vmx/vmx.c        Tue Jul 10 23:37:42 2007 +0100
@@ -2718,7 +2718,7 @@ static void vmx_free_vlapic_mapping(stru
 
 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(s
     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);
 }
 

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