Re: [PATCH] selftests: kvm: Mmap the entire vcpu mmap area

Andrew Jones
2021-02-10T17:43:48Z

On Wed, Feb 10, 2021 at 08:50:36AM -0800, Aaron Lewis wrote:
> The vcpu mmap area may consist of more than just the kvm_run struct.
> Allocate enough space for the entire vcpu mmap area. Without this, on
> x86, the PIO page, for example, will be missing. This is problematic
> when dealing with an unhandled exception from the guest as the exception
> vector will be incorrectly reported as 0x0.
>
> Signed-off-by: Aaron Lewis <aaronlewis@google.com>
> Signed-off-by: Steve Rutherford <srutherford@google.com>
> ---
> tools/testing/selftests/kvm/lib/kvm_util.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
> index fa5a90e6c6f0..859a0b57c683 100644
> --- a/tools/testing/selftests/kvm/lib/kvm_util.c
> +++ b/tools/testing/selftests/kvm/lib/kvm_util.c
> @@ -21,6 +21,8 @@
> #define KVM_UTIL_PGS_PER_HUGEPG 512
> #define KVM_UTIL_MIN_PFN 2
>
> +static int vcpu_mmap_sz(void);
> +
> /* Aligns x up to the next multiple of size. Size must be a power of 2. */
> static void *align(void *x, size_t size)
> {
> @@ -509,7 +511,7 @@ static void vm_vcpu_rm(struct kvm_vm *vm, struct vcpu *vcpu)
> vcpu->dirty_gfns = NULL;
> }
>
> - ret = munmap(vcpu->state, sizeof(*vcpu->state));
> + ret = munmap(vcpu->state, vcpu_mmap_sz());
> TEST_ASSERT(ret == 0, "munmap of VCPU fd failed, rc: %i "
> "errno: %i", ret, errno);
> close(vcpu->fd);
> @@ -978,7 +980,7 @@ void vm_vcpu_add(struct kvm_vm *vm, uint32_t vcpuid)
> TEST_ASSERT(vcpu_mmap_sz() >= sizeof(*vcpu->state), "vcpu mmap size "
> "smaller than expected, vcpu_mmap_sz: %i expected_min: %zi",
> vcpu_mmap_sz(), sizeof(*vcpu->state));
> - vcpu->state = (struct kvm_run *) mmap(NULL, sizeof(*vcpu->state),
> + vcpu->state = (struct kvm_run *) mmap(NULL, vcpu_mmap_sz(),
> PROT_READ | PROT_WRITE, MAP_SHARED, vcpu->fd, 0);
> TEST_ASSERT(vcpu->state != MAP_FAILED, "mmap vcpu_state failed, "
> "vcpu id: %u errno: %i", vcpuid, errno);
> --
> 2.30.0.478.g8a0d178c01-goog
>

Reviewed-by: Andrew Jones <drjones@redhat.com>