Re: [PATCH kvm-unit-tests] x86: Check DR6.RTM is writable

Paolo Bonzini
2014-07-21T15:20:55Z

Il 15/07/2014 16:41, Nadav Amit ha scritto:
> Recently discovered bug shows DR6.RTM is fixed to one. The bug is only apparent
> when the host emulates the MOV-DR instruction or when the host debugs the
> guest kernel. This patch tests whether DR6.RTM is indeed accessible according
> to RTM support as reported by cpuid.
>
> Signed-off-by: Nadav Amit <namit@cs.technion.ac.il>
> ---
> x86/emulator.c | 15 +++++++++++++++
> 1 file changed, 15 insertions(+)
>
> diff --git a/x86/emulator.c b/x86/emulator.c
> index 1fd0ca6..f68882f 100644
> --- a/x86/emulator.c
> +++ b/x86/emulator.c
> @@ -3,6 +3,7 @@
> #include "libcflat.h"
> #include "desc.h"
> #include "types.h"
> +#include "processor.h"
>
> #define memset __builtin_memset
> #define TESTDEV_IO_PORT 0xe0
> @@ -870,6 +871,19 @@ static void test_nop(uint64_t *mem, uint8_t *insn_page,
> report("nop", outregs.rax == inregs.rax);
> }
>
> +static void test_mov_dr(uint64_t *mem, uint8_t *insn_page,
> + uint8_t *alt_insn_page, void *insn_ram)
> +{
> + bool rtm_support = cpuid(7).b & (1 << 11);
> + unsigned long dr6_fixed_1 = rtm_support ? 0xfffe0ff0ul : 0xffff0ff0ul;
> + inregs = (struct regs){ .rax = 0 };
> + MK_INSN(mov_to_dr6, "movq %rax, %dr6\n\t");
> + trap_emulator(mem, alt_insn_page, &insn_mov_to_dr6);
> + MK_INSN(mov_from_dr6, "movq %dr6, %rax\n\t");
> + trap_emulator(mem, alt_insn_page, &insn_mov_from_dr6);
> + report("mov_dr6", outregs.rax == dr6_fixed_1);
> +}
> +
> static void test_crosspage_mmio(volatile uint8_t *mem)
> {
> volatile uint16_t w, *pw;
> @@ -1072,6 +1086,7 @@ int main()
> test_movabs(mem, insn_page, alt_insn_page, insn_ram);
> test_smsw_reg(mem, insn_page, alt_insn_page, insn_ram);
> test_nop(mem, insn_page, alt_insn_page, insn_ram);
> + test_mov_dr(mem, insn_page, alt_insn_page, insn_ram);
> test_crosspage_mmio(mem);
>
> test_string_io_mmio(mem);
>

Thanks, applying.

Paolo