Il 05/12/2013 17:12, Laszlo Ersek ha scritto: > Hi, > > I'm working on S3 suspend/resume in OVMF. The problem is that I'm getting an > unexpected guest reboot for code (LRET) that works on physical hardware. I > tried to trace the problem with ftrace, but I didn't get any mentions of > em_ret_far(). (Maybe I was looking in the wrong place.)
What does ftrace say anyway? > Please find the the assembly-language "trampoline" that is invoked (in 64-bit > mode) with the 16-bit real mode resume vector placed in "rcx" (EFIAPI calling > convention). The excerpt is from the edk2 tree, > "MdeModulePkg/Universal/Acpi/BootScriptExecutorDxe/X64/S3Asm.S". Can you send me a pointer to a git tree or, even better, an OVMF.fd file + instructions on how to trigger the problem? > - shared properties: > Base=0x00000000 > Limit=0xFFFFF > Type=0xB (C ER A ) > S=0x1 (code/data) > DPL=0x0 > Present=1 > Avail=0 > LimitGran=0x1 (4KB) > > - different properties: > 0x0010: 0x00CF9B000000FFFF: 64-bitC=0 D/B=1 works > 0x0028: 0x008F9B000000FFFF: 64-bitC=0 D/B=0 reboots > 0x0038: 0x00AF9B000000FFFF: 64-bitC=1 D/B=0 works > > That is: > - if I let 64-bit mode execution enabled (64-bitC=1, desc 0x38), the lret > works. > - If I switch to compat mode execution (64-bitC=0, desc 0x10), *and* keep the > default addr/op size 32 bits, the lret still works. Perhaps you could try switching to 32-bit mode first, then disable paging, then jump to 16-bit mode. Like this (untested): diff --git a/MdeModulePkg/Universal/Acpi/BootScriptExecutorDxe/X64/S3Asm.S b/MdeModulePkg/Universal/Acpi/BootScriptExecutorDxe/X64/S3Asm.S index e59fd04..d1cac9d 100644 --- a/MdeModulePkg/Universal/Acpi/BootScriptExecutorDxe/X64/S3Asm.S +++ b/MdeModulePkg/Universal/Acpi/BootScriptExecutorDxe/X64/S3Asm.S @@ -19,7 +19,7 @@ ASM_PFX(AsmTransferControl): # rcx S3WakingVector :DWORD # rdx AcpiLowMemoryBase :DWORD lea _AsmTransferControl_al_0000(%rip), %eax - movq $0x2800000000, %r8 + movq $0x1000000000, %r8 orq %r8, %rax pushq %rax shrd $20, %ecx, %ebx @@ -28,24 +28,32 @@ ASM_PFX(AsmTransferControl): movl %ebx, jmp_addr(%rip) lret _AsmTransferControl_al_0000: + # Old SS should still be okay? + addl _AsmTransferControl_al_0001-_AsmTransferControl_al_0000, %eax + pushl $0x28 + pushl %eax + movq %cr0, %rax + movq %cr4, %rbx + andl $0x7fffffff, %eax + andb $0xdf, %bl + movq %rax, %cr0 # sets EFER.LMA=0 too, so says Intel + movl $0x0c0000080, %ecx + rdmsr + andb $0xfe, %ah # set EFER.LME=0 + wrmsr + movq %rbx, %cr4 # only now set CR4.PAE=0 + lret +_AsmTransferControl_al_0001: .byte 0x0b8, 0x30, 0 # mov ax, 30h as selector movl %eax, %ds movl %eax, %es movl %eax, %fs movl %eax, %gs movl %eax, %ss - movq %cr0, %rax - movq %cr4, %rbx - .byte 0x66 - andl $0x7ffffffe, %eax - andb $0xdf, %bl - movq %rax, %cr0 - .byte 0x66 - movl $0x0c0000080, %ecx - rdmsr - andb $0xfe, %ah - wrmsr - movq %rbx, %cr4 + movl %cr0, %rax # Get control register 0 + .byte 0x66 + .byte 0x83,0xe0,0xfe # and eax, 0fffffffeh ; Clear PE bit (bit #0) + .byte 0xf,0x22,0xc0 # mov cr0, eax ; Activate real mode > - If I switch to compat mode execution (64-bitC=0, desc 0x28), but also change > the default addr/op size to 16-bits, then the lret reboots the guest in KVM > (but works on physical hardware). Did you try this on physical hardware, or just assumed that? :) Paolo ------------------------------------------------------------------------------ Sponsored by Intel(R) XDK Develop, test and display web and hybrid apps with a single code base. Download it for free now! http://pubads.g.doubleclick.net/gampad/clk?id=111408631&iu=/4140/ostg.clktrk _______________________________________________ edk2-devel mailing list edk2-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/edk2-devel