diff options
| author | Laurent Vivier <Laurent.Vivier@bull.net> | 2007-10-25 14:18:55 +0200 |
|---|---|---|
| committer | Avi Kivity <avi@qumranet.com> | 2008-01-30 17:52:56 +0200 |
| commit | ff593e5abebd899b0b41c11280e2fbeff4103375 (patch) | |
| tree | d4ebafad5ab7a358114e82acd251379d01ba6855 /drivers/kvm/vmx.c | |
| parent | c20363006af64cf397519da5e984b18e6bdffd82 (diff) | |
KVM: VMX: Let gcc to choose which registers to save (i386)
This patch lets GCC to determine which registers to save when we
switch to/from a VCPU in the case of intel i386.
* 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 <Laurent.Vivier@bull.net>
Signed-off-by: Avi Kivity <avi@qumranet.com>
Diffstat (limited to 'drivers/kvm/vmx.c')
| -rw-r--r-- | 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 56c9bcc8283..2d7d638d72d 100644 --- a/drivers/kvm/vmx.c +++ b/drivers/kvm/vmx.c @@ -2268,7 +2268,8 @@ 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 */ @@ -2342,9 +2343,8 @@ 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) @@ -2372,6 +2372,8 @@ 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 ); |