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| author | Ricardo Koller <ricarkol@google.com> | 2021-06-10 18:10:16 -0700 |
|---|---|---|
| committer | Marc Zyngier <maz@kernel.org> | 2021-06-14 09:06:22 +0100 |
| commit | b7326c01122683b88e273a0cc826cd4c01234470 (patch) | |
| tree | 088da6a9d8b2f05912cd674d7af035b52b5f5319 | |
| parent | b78f4a596692f6805e796a4c13f2d921b8a95166 (diff) | |
| download | linux-b7326c01122683b88e273a0cc826cd4c01234470.tar.bz2 | |
KVM: selftests: Complete x86_64/sync_regs_test ucall
The guest in sync_regs_test does raw ucalls by directly accessing the
ucall IO port. It makes these ucalls without setting %rdi to a `struct
ucall`, which is what a ucall uses to pass messages. The issue is that
if the host did a get_ucall (the receiver side), it would try to access
the `struct ucall` at %rdi=0 which would lead to an error ("No mapping
for vm virtual address, gva: 0x0").
This issue is currently benign as there is no get_ucall in
sync_regs_test; however, that will change in the next commit as it
changes the unhandled exception reporting mechanism to use ucalls. In
that case, every vcpu_run is followed by a get_ucall to check if the
guest is trying to report an unhandled exception.
Fix this in advance by setting %rdi to a UCALL_NONE struct ucall for the
sync_regs_test guest.
Tested with gcc-[8,9,10], and clang-[9,11].
Signed-off-by: Ricardo Koller <ricarkol@google.com>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210611011020.3420067-3-ricarkol@google.com
| -rw-r--r-- | tools/testing/selftests/kvm/x86_64/sync_regs_test.c | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/tools/testing/selftests/kvm/x86_64/sync_regs_test.c b/tools/testing/selftests/kvm/x86_64/sync_regs_test.c index d672f0a473f8..fc03a150278d 100644 --- a/tools/testing/selftests/kvm/x86_64/sync_regs_test.c +++ b/tools/testing/selftests/kvm/x86_64/sync_regs_test.c @@ -24,6 +24,10 @@ #define UCALL_PIO_PORT ((uint16_t)0x1000) +struct ucall uc_none = { + .cmd = UCALL_NONE, +}; + /* * ucall is embedded here to protect against compiler reshuffling registers * before calling a function. In this test we only need to get KVM_EXIT_IO @@ -34,7 +38,8 @@ void guest_code(void) asm volatile("1: in %[port], %%al\n" "add $0x1, %%rbx\n" "jmp 1b" - : : [port] "d" (UCALL_PIO_PORT) : "rax", "rbx"); + : : [port] "d" (UCALL_PIO_PORT), "D" (&uc_none) + : "rax", "rbx"); } static void compare_regs(struct kvm_regs *left, struct kvm_regs *right) |