From: Bill Burns <bburns@redhat.com>
Date: Wed, 16 Apr 2008 08:41:17 -0400
Subject: [xen] fix VT-x2 FlexPriority
Message-id: 20080416124117.4800.46884.sendpatchset@localhost.localdomain
O-Subject: [RHEL5.2 PATCH] Xen Fix VT-x2 FlexPriority (vTPR)
Bugzilla: 252236

Fixes bz 252236

https://bugzilla.redhat.com/show_bug.cgi?id=252236

The Intel feature request for VT-x2 FlexPriority (aka vTPR)
was incorporated into RHEL 5.2 automatically due to the rebase
to the 3.1.2 Hypervisor. However, there was a patch specified
in the BZ that was not part of 3.1.2 and is needed to prevent
Windows guests from 'blue screening'.

Code is upstream in 3.1 cset 15572, located at

http://xenbits.xensource.com/staging/xen-3.1-testing.hg?rev/690a80169633

This patch is a slight variation of that patch since 15572 relied
upon some changes made in other post 3.1.2 patches. This modification
was provided by Intel.

It has been brew built and tested out locally. QA has been
asked to give it some mileage as well.

Please review and ACK.

Thanks,
 Bill

Derived from n 3.1-testing changeset 15572
author: 	Keir Fraser <keir.fraser@citrix.com>
date: 	Thu Dec 27 22:57:41 2007 +0000

description: 	vmx: Do not allow emulated accesses to the vlapic mmap'ed 'magic
page'.

This is the equivalent of:
xen-unstable changeset: 16663:d5f0afb58589
xen-unstable date: Thu Dec 27 12:03:02 2007 +0000

Acked-by: "Stephen C. Tweedie" <sct@redhat.com>
Acked-by: Chris Lalancette <clalance@redhat.com>
Acked-by: Rik van Riel <riel@redhat.com>

diff --git a/arch/x86/hvm/hvm.c b/arch/x86/hvm/hvm.c
index 00c1c86..208f14b 100644
--- a/arch/x86/hvm/hvm.c
+++ b/arch/x86/hvm/hvm.c
@@ -240,6 +240,8 @@ int hvm_domain_initialise(struct domain *d)
         return -EINVAL;
     }
 
+    d->arch.hvm_domain.vmx_apic_access_mfn = INVALID_MFN;
+
     spin_lock_init(&d->arch.hvm_domain.pbuf_lock);
     spin_lock_init(&d->arch.hvm_domain.irq_lock);
     spin_lock_init(&d->arch.hvm_domain.vapic_access_lock);
@@ -598,7 +600,8 @@ static int __hvm_copy(void *buf, paddr_t addr, int size, int dir, int virt)
         
         mfn = get_mfn_from_gpfn(gfn);
 
-        if ( mfn == INVALID_MFN )
+        if ( (mfn == current->domain->arch.hvm_domain.vmx_apic_access_mfn) ||
+             (mfn == INVALID_MFN) )
             return todo;
 
         p = (char *)map_domain_page(mfn) + (addr & ~PAGE_MASK);
diff --git a/arch/x86/hvm/vmx/vmx.c b/arch/x86/hvm/vmx/vmx.c
index 777a7b3..51b058d 100644
--- a/arch/x86/hvm/vmx/vmx.c
+++ b/arch/x86/hvm/vmx/vmx.c
@@ -2655,6 +2655,7 @@ struct page_info * change_guest_physmap_for_vtpr(struct domain *d,
 
         mfn = page_to_mfn(pg);
         d->arch.hvm_domain.apic_access_page = pg;
+        d->arch.hvm_domain.vmx_apic_access_mfn = mfn;
 
         guest_physmap_add_page(d, pfn, mfn);
 
diff --git a/arch/x86/mm/shadow/multi.c b/arch/x86/mm/shadow/multi.c
index 2279451..271d124 100644
--- a/arch/x86/mm/shadow/multi.c
+++ b/arch/x86/mm/shadow/multi.c
@@ -4012,7 +4012,8 @@ static inline void * emulate_map_dest(struct vcpu *v,
     if ( !(flags & _PAGE_RW) ) 
         goto page_fault;
 
-    if ( mfn_valid(mfn) )
+    if ( mfn_valid(mfn) &&
+         (mfn_x(mfn) != v->domain->arch.hvm_domain.vmx_apic_access_mfn) )
     {
         *mfnp = mfn;
         v->arch.paging.last_write_was_pt = !!sh_mfn_is_a_page_table(mfn);
diff --git a/include/asm-x86/hvm/domain.h b/include/asm-x86/hvm/domain.h
index 3c8d54e..50802b3 100644
--- a/include/asm-x86/hvm/domain.h
+++ b/include/asm-x86/hvm/domain.h
@@ -45,6 +45,7 @@ struct hvm_domain {
     spinlock_t             vapic_access_lock;
     int                    physmap_changed_for_vlapic_access : 1;
     struct page_info       *apic_access_page;
+    unsigned long          vmx_apic_access_mfn;
 
     struct hvm_io_handler  io_handler;