[Xen-changelog] [xen master] hvm/hpet: correctly gate the virtual HPET on HVM_PARAM_HPET_ENABLE

[patchbot@xxxxxxx]

commit 433468d3b025fdb5b612df27a3b4347ae53ffb77
Author:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
AuthorDate: Mon Jan 19 12:16:44 2015 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Mon Jan 19 12:16:44 2015 +0100

    hvm/hpet: correctly gate the virtual HPET on HVM_PARAM_HPET_ENABLE
    
    c/s 3f8e22de7 "x86 hvm: Allow HPET to be configured as a per-domain config
    option" introduced the parameter to conditionally enable the HPET.
    
    However, having the check in hpet_range() does not have the intended effect.
    As currently implemented, when the HPET is disabled, the range is not 
claimed
    and an ioreq is forwarded to qemu, which implements an HPET itself.
    
    Properly disable the HPET by always claiming the range, dropping writes and
    reading ~0.
    
    Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
 xen/arch/x86/hvm/hpet.c |   14 +++++++++++---
 1 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/xen/arch/x86/hvm/hpet.c b/xen/arch/x86/hvm/hpet.c
index bdfc6fc..d898169 100644
--- a/xen/arch/x86/hvm/hpet.c
+++ b/xen/arch/x86/hvm/hpet.c
@@ -173,6 +173,12 @@ static int hpet_read(
     unsigned long result;
     uint64_t val;
 
+    if ( !v->domain->arch.hvm_domain.params[HVM_PARAM_HPET_ENABLED] )
+    {
+        result = ~0ul;
+        goto out;
+    }
+
     addr &= HPET_MMAP_SIZE-1;
 
     if ( hpet_check_access_length(addr, length) != 0 )
@@ -309,6 +315,9 @@ static int hpet_write(
 #define set_start_timer(n)   (__set_bit((n), &start_timers))
 #define set_restart_timer(n) (set_stop_timer(n),set_start_timer(n))
 
+    if ( !v->domain->arch.hvm_domain.params[HVM_PARAM_HPET_ENABLED] )
+        goto out;
+
     addr &= HPET_MMAP_SIZE-1;
 
     if ( hpet_check_access_length(addr, length) != 0 )
@@ -491,9 +500,8 @@ static int hpet_write(
 
 static int hpet_range(struct vcpu *v, unsigned long addr)
 {
-    return (v->domain->arch.hvm_domain.params[HVM_PARAM_HPET_ENABLED] &&
-            (addr >= HPET_BASE_ADDRESS) &&
-            (addr < (HPET_BASE_ADDRESS + HPET_MMAP_SIZE)));
+    return ( (addr >= HPET_BASE_ADDRESS) &&
+             (addr < (HPET_BASE_ADDRESS + HPET_MMAP_SIZE)) );
 }
 
 const struct hvm_mmio_handler hpet_mmio_handler = {
--
generated by git-patchbot for /home/xen/git/xen.git#master

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