This patch lets GCC to determine which registers to save when we
switch to/from a VCPU in the case of intel i386.

>>> I don't know if its patch is really usefull as it replaces <<<
>>> a popa/pusha by several pop/push.                          <<<

* Original code saves following registers:
    
    eax, ebx, ecx, edx, edi, esi, ebp (using popa)

* Patched code:

  - informs GCC that we modify following registers
    using the clobber description:

    ebx, edi, rsi

  - doesn't save eax because it is an output operand (vmx->fail)

  - cannot put ecx in clobber description because it is an input operand,
    but as we modify it and we want to keep its value (vcpu), we must
    save it (pop/push)

  - ebp is saved (pop/push) because GCC seems to ignore its use the clobber
    description.

  - edx is saved (pop/push) because it is reserved by GCC (REGPARM) and
    cannot be put in the clobber description.

  - line "mov (%%esp), %3 \n\t" has been removed because %3
    is ecx and ecx is restored just after.
    
Signed-off-by: Laurent Vivier <[EMAIL PROTECTED]>
---
 drivers/kvm/vmx.c |    8 +++++---
 1 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/kvm/vmx.c b/drivers/kvm/vmx.c
index ec81ebc..890419a 100644
--- a/drivers/kvm/vmx.c
+++ b/drivers/kvm/vmx.c
@@ -2245,7 +2245,8 @@ static void vmx_vcpu_run(struct kvm_vcpu *vcpu, struct 
kvm_run *kvm_run)
                "push %%rdx; push %%rbp;"
                "push %%rcx \n\t"
 #else
-               "pusha; push %%ecx \n\t"
+               "push %%edx; push %%ebp;"
+               "push %%ecx \n\t"
 #endif
                ASM_VMX_VMWRITE_RSP_RDX "\n\t"
                /* Check if vmlaunch of vmresume is needed */
@@ -2319,9 +2320,8 @@ static void vmx_vcpu_run(struct kvm_vcpu *vcpu, struct 
kvm_run *kvm_run)
                "mov %%ebp, %c[rbp](%3) \n\t"
                "mov %%cr2, %%eax  \n\t"
                "mov %%eax, %c[cr2](%3) \n\t"
-               "mov (%%esp), %3 \n\t"
 
-               "pop %%ecx; popa \n\t"
+               "pop %%ecx; pop %%ebp; pop %%edx \n\t"
 #endif
                "setbe %0 \n\t"
              : "=q" (vmx->fail)
@@ -2349,6 +2349,8 @@ static void vmx_vcpu_run(struct kvm_vcpu *vcpu, struct 
kvm_run *kvm_run)
 #ifdef CONFIG_X86_64
                , "rbx", "rdi", "rsi"
                , "r8", "r9", "r10", "r11", "r12", "r13", "r14", "r15"
+#else
+               , "ebx", "edi", "rsi"
 #endif
              );
 
-- 
1.5.2.4


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