On Thu, May 20, 2021 at 3:06 PM Krish Sadhukhan
<krish.sadhukhan@xxxxxxxxxx> wrote:
>
> According to section "Canonicalization and Consistency Checks" in APM vol 2,
>
> VMRUN canonicalizes (i.e., sign-extend to bit 63) all base addresses
> in the segment registers that have been loaded.
>
> Signed-off-by: Krish Sadhukhan <krish.sadhukhan@xxxxxxxxxx>
> ---
> x86/svm_tests.c | 29 +++++++++++++++++++++++++++++
> 1 file changed, 29 insertions(+)
>
> diff --git a/x86/svm_tests.c b/x86/svm_tests.c
> index d689e73..8387bea 100644
> --- a/x86/svm_tests.c
> +++ b/x86/svm_tests.c
> @@ -2499,6 +2499,34 @@ static void test_msrpm_iopm_bitmap_addrs(void)
> vmcb->control.intercept = saved_intercept;
> }
>
> +#define TEST_CANONICAL(seg_base, msg) \
> + saved_addr = seg_base; \
> + seg_base = (seg_base & ((1ul << addr_limit) - 1)) | noncanonical_mask; \
> + report(svm_vmrun() == SVM_EXIT_VMMCALL, "Test %s.base for canonical form: %lx", msg, seg_base); \
> + seg_base = saved_addr;
This is messy. Why not just set seg_base to NONCANONICAL before
svm_vmrun() and then check to see that it's equal to
canonicalize(NONCANONICAL) after #VMEXIT?
> +/*
> + * VMRUN canonicalizes (i.e., sign-extend to bit 63) all base addresses
> + • in the segment registers that have been loaded.
> + */
> +static void test_vmrun_canonicalization(void)
> +{
> + u64 saved_addr;
> + u8 addr_limit = cpuid_maxphyaddr();
What constitutes a canonical address depends on the maximum *virtual*
address width supported, not the maximum physical address width
supported.
> + u64 noncanonical_mask = NONCANONICAL & ~((1ul << addr_limit) - 1);
> +
> + TEST_CANONICAL(vmcb->save.es.base, "ES");
> + TEST_CANONICAL(vmcb->save.cs.base, "CS");
> + TEST_CANONICAL(vmcb->save.ss.base, "SS");
> + TEST_CANONICAL(vmcb->save.ds.base, "DS");
> + TEST_CANONICAL(vmcb->save.fs.base, "FS");
> + TEST_CANONICAL(vmcb->save.gs.base, "GS");
> + TEST_CANONICAL(vmcb->save.gdtr.base, "GDTR");
> + TEST_CANONICAL(vmcb->save.ldtr.base, "LDTR");
> + TEST_CANONICAL(vmcb->save.idtr.base, "IDTR");
> + TEST_CANONICAL(vmcb->save.tr.base, "TR");
There are only 8 segment registers. GDTR and IDTR are not segment
registers. They may be canonicalized by VMRUN/#VMEXIT, but they are
not segment registers.
> +}
> +
> static void svm_guest_state_test(void)
> {
> test_set_guest(basic_guest_main);
> @@ -2508,6 +2536,7 @@ static void svm_guest_state_test(void)
> test_cr4();
> test_dr();
> test_msrpm_iopm_bitmap_addrs();
> + test_vmrun_canonicalization();
> }
>
>
> --
> 2.27.0
>
