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bluepill/exit_handler.cpp

234 lines
6.0 KiB

#include "vmxexit_handler.h"
auto vmresume_failure() -> void
{
size_t value;
__vmx_vmread(VMCS_VM_INSTRUCTION_ERROR, &value);
dbg::print("> vmresume error... reason = 0x%x\n", value);
}
auto exit_handler(hv::pguest_registers regs) -> void
{
u64 exit_reason;
__vmx_vmread(VMCS_EXIT_REASON, &exit_reason);
switch (exit_reason)
{
case VMX_EXIT_REASON_EXECUTE_CPUID:
{
int result[4];
__cpuid(result, regs->rax);
regs->rax = result[0];
regs->rbx = result[1];
regs->rcx = result[2];
regs->rdx = result[3];
goto advance_rip;
}
// shouldnt get an exit when the LP is already executing an NMI...
// so it should be safe to inject an NMI here...
case VMX_EXIT_REASON_NMI_WINDOW:
{
exception::injection(interruption_type::non_maskable_interrupt, EXCEPTION_NMI);
// turn off NMI window exiting since we handled the NMI...
ia32_vmx_procbased_ctls_register procbased_ctls;
__vmx_vmread(VMCS_CTRL_PROCESSOR_BASED_VM_EXECUTION_CONTROLS, &procbased_ctls.flags);
procbased_ctls.nmi_window_exiting = false;
__vmx_vmwrite(VMCS_CTRL_PROCESSOR_BASED_VM_EXECUTION_CONTROLS, procbased_ctls.flags);
goto dont_advance;
}
case VMX_EXIT_REASON_EXECUTE_XSETBV:
{
hv::msr_split value{};
value.high = regs->rdx;
value.low = regs->rax;
__try
{
/*
EXCEPTION WARNING:
#GP If the current privilege level is not 0.
If an invalid XCR is specified in ECX.
If the value in EDX:EAX sets bits that are reserved in the XCR specified by ECX.
If an attempt is made to clear bit 0 of XCR0.
If an attempt is made to set XCR0[2:1] to 10b.
#UD If CPUID.01H:ECX.XSAVE[bit 26] = 0.
If CR4.OSXSAVE[bit 18] = 0.
If the LOCK prefix is used.
*/
_xsetbv(regs->rcx, value.value);
goto advance_rip;
}
__except (EXCEPTION_EXECUTE_HANDLER)
{
exception::injection(interruption_type::hardware_exception,
EXCEPTION_GP_FAULT, { true, g_vcpu.error_code });
goto dont_advance;
}
}
case VMX_EXIT_REASON_EXECUTE_RDMSR:
{
__try
{
/*
EXCEPTION WARNING:
#GP(0) If the current privilege level is not 0.
If the value in ECX specifies a reserved or unimplemented MSR address.
#UD If the LOCK prefix is used.
*/
const auto result =
hv::msr_split{ __readmsr(regs->rcx) };
regs->rdx = result.high;
regs->rax = result.low;
goto advance_rip;
}
__except (EXCEPTION_EXECUTE_HANDLER)
{
exception::injection(interruption_type::hardware_exception,
EXCEPTION_GP_FAULT, { true, g_vcpu.error_code });
goto dont_advance;
}
}
case VMX_EXIT_REASON_EXECUTE_WRMSR:
{
hv::msr_split value;
value.low = regs->rax;
value.high = regs->rdx;
__try
{
/*
EXCEPTION WARNING:
#GP(0) If the current privilege level is not 0.
If the value in ECX specifies a reserved or unimplemented MSR address.
#UD If the LOCK prefix is used.
*/
__writemsr(regs->rcx, value.value);
goto advance_rip;
}
__except (EXCEPTION_EXECUTE_HANDLER)
{
exception::injection(interruption_type::hardware_exception,
EXCEPTION_GP_FAULT, { true, g_vcpu.error_code });
goto dont_advance;
}
}
case VMX_EXIT_REASON_EXECUTE_INVD:
{
__wbinvd();
goto advance_rip;
}
case VMX_EXIT_REASON_EXECUTE_VMCALL:
{
if (regs->rcx == VMCALL_KEY)
{
cr3 dirbase;
__vmx_vmread(VMCS_GUEST_CR3, &dirbase.flags);
auto command = command::get(
dirbase.pml4_pfn << 12, regs->rdx);
if (!command.present)
{
exception::injection(interruption_type::hardware_exception, EXCEPTION_INVALID_OPCODE);
goto dont_advance;
}
switch (command.option)
{
case command::vmcall_option::copy_virt:
{
command.result =
mm::copy_virt(
command.copy_virt.dirbase_src,
command.copy_virt.virt_src,
command.copy_virt.dirbase_dest,
command.copy_virt.virt_dest,
command.copy_virt.size);
break;
}
case command::vmcall_option::translate:
{
command.translate.phys_addr =
mm::translate(mm::virt_addr_t{
command.translate.virt_addr },
command.translate.dirbase);
// true if address is not null...
command.result = command.translate.phys_addr;
break;
}
case command::vmcall_option::read_phys:
{
command.result =
mm::read_phys(
command.read_phys.dirbase_dest,
command.read_phys.phys_src,
command.read_phys.virt_dest,
command.read_phys.size);
break;
}
case command::vmcall_option::write_phys:
{
command.result =
mm::write_phys(
command.write_phys.dirbase_src,
command.write_phys.phys_dest,
command.write_phys.virt_src,
command.write_phys.size);
break;
}
case command::vmcall_option::dirbase:
{
command.result = true;
command.dirbase = dirbase.pml4_pfn << 12;
break;
}
default:
// check to see why the option was invalid...
__debugbreak();
}
command::set(dirbase.pml4_pfn << 12, regs->rdx, command);
goto advance_rip;
}
else
{
exception::injection(interruption_type::hardware_exception, EXCEPTION_INVALID_OPCODE);
goto dont_advance;
}
}
case VMX_EXIT_REASON_EXECUTE_VMWRITE:
case VMX_EXIT_REASON_EXECUTE_VMREAD:
case VMX_EXIT_REASON_EXECUTE_VMPTRST:
case VMX_EXIT_REASON_EXECUTE_VMPTRLD:
case VMX_EXIT_REASON_EXECUTE_VMCLEAR:
case VMX_EXIT_REASON_EXECUTE_VMXOFF:
case VMX_EXIT_REASON_EXECUTE_VMXON:
case VMX_EXIT_REASON_EXECUTE_VMFUNC:
{
exception::injection(interruption_type::hardware_exception, EXCEPTION_INVALID_OPCODE);
goto dont_advance;
}
default:
// TODO: check out the vmexit reason and add support for it...
__debugbreak();
}
advance_rip:
size_t rip, exec_len;
__vmx_vmread(VMCS_GUEST_RIP, &rip);
__vmx_vmread(VMCS_VMEXIT_INSTRUCTION_LENGTH, &exec_len);
__vmx_vmwrite(VMCS_GUEST_RIP, rip + exec_len);
// since we are advancing RIP, also check if TF = 1, if so, set pending #DB...
// otherwise this #DB will fire on the wrong instruction... please refer to:
// https://howtohypervise.blogspot.com/2019/01/a-common-missight-in-most-hypervisors.html
exception::handle_debug();
dont_advance:
return;
}