bug fix for 32 bit ebp cloberring

[palacios.git] / palacios / src / palacios / svm_lowlevel.S

diff --git a/palacios/src/palacios/svm_lowlevel.S b/palacios/src/palacios/svm_lowlevel.S
index 975fe98..45c5575 100644 (file)
--- a/palacios/src/palacios/svm_lowlevel.S
+++ b/palacios/src/palacios/svm_lowlevel.S
@@ -1,6 +1,5 @@
 #;  -*- fundamental -*-
 
-
 .text
 .align 4
 
@@ -18,8 +17,13 @@
 #define clgi   .byte 0x0F,0x01,0xDD
 
 
+#define SVM_VM_HSAVE_PA_MSR .dword 0xc0010117
+
+
 #ifdef __V3_32BIT__
 
+// Note that RAX is saved in the VMCB, so we don't touch it here
+
 #define Save_SVM_Registers(location)   \
        pushl   %eax;                   \
        movl    location, %eax;         \
@@ -30,10 +34,6 @@
        movl    %ebx, 32(%eax);         \
        movl    %edx, 40(%eax);         \
        movl    %ecx, 48(%eax);         \
-       pushl   %ebx;                   \
-       movl    8(%esp), %ebx;          \
-       movl    %ebx, 56(%eax);         \
-       popl    %ebx;                   \
        popl    %eax;                   
        
 
@@ -49,14 +49,17 @@
        popl    %eax;
 
 
+// 32 bit GCC passes arguments via stack
+
 v3_svm_launch:
        push    %ebp;
        movl    %esp, %ebp;
        pushf;
-       push    %fs;
-       push    %gs;
        pusha;
 
+       movl    16(%ebp), %eax;
+       vmsave;
+
        pushl   12(%ebp);
        pushl   8(%ebp);
 
@@ -72,9 +75,14 @@ v3_svm_launch:
        addl    $4, %esp;
 
        popa;
-       pop     %gs;
-       pop     %fs;
        popf;
+
+       movl    16(%ebp), %eax;
+       vmload;
+
+       // We don't detect failures here, so just return 0
+       xorl    %eax, %eax 
+
        pop     %ebp;
        ret
 
@@ -82,6 +90,8 @@ v3_svm_launch:
 
 #elif __V3_64BIT__
 
+// Note that RAX is saved in the VMCB, so we don't touch it here
+
 #define Save_SVM_Registers(location)   \
        pushq   %rax;                   \
        movq    location, %rax;         \
@@ -92,10 +102,6 @@ v3_svm_launch:
        movq    %rbx, 32(%rax);         \
        movq    %rdx, 40(%rax);         \
        movq    %rcx, 48(%rax);         \
-       pushq   %rbx;                   \
-       movq    16(%rsp), %rbx;         \
-       movq    %rbx, 56(%rax);         \
-       popq    %rbx;                   \
                                        \
        movq    %r8, 64(%rax);          \
        movq    %r9, 72(%rax);          \
@@ -156,29 +162,19 @@ v3_svm_launch:
        popq %rbx;                      \
        popq %rbp;                      
 
+
+// Note that this is only for 64 bit GCC, 32 bit GCC passes via stack
 // VMCB => RDI
 // vm_regs => RSI
-// ptr to fs => RDX
-// ptr to gs => RCX
+// HOST VMCB => RDX
 
 v3_svm_launch:
        pushf;
-       push    %fs;
-       push    %gs;
        PUSHA
-
-
-
-//     pushq   %rdx // fs
-//     pushq   %rcx // gs
-
-
-//     pushq   (%rdx)
-//     pop     %fs
-//     pushq   (%rcx)
-//     pop     %gs
-
-
+       
+       pushq   %rdx;
+       movq    %rdx, %rax;
+       vmsave;
 
        pushq   %rsi
 
@@ -195,21 +191,11 @@ v3_svm_launch:
 
        addq $8, %rsp
 
-//     popq    %rcx
-//     popq    %rdx
-
-//     push    %fs
-//     popq    %rax
-//     movq    %rax, (%rdx)
-
-//     push    %gs
-//     popq    %rax
-//     movq    %rax, (%rcx)
 
+       popq %rax;
+       vmload;
 
        POPA
-       pop     %gs;
-       pop     %fs;
        popf;
        ret