On Tue, 2022-02-08 at 14:27 +0100, Pierre Morel wrote:
> We need in several tests to check if the VM we are running in
> is KVM.
> Let's add the test.
>
> To check the VM type we use the STSI 3.2.2 instruction, let's
> define it's response structure in a central header.
>
> Signed-off-by: Pierre Morel <pmorel@xxxxxxxxxxxxx>
> ---
> lib/s390x/stsi.h | 32 +++++++++++++++++++++++++++
> lib/s390x/vm.c | 56
> ++++++++++++++++++++++++++++++++++++++++++++++--
> lib/s390x/vm.h | 3 +++
> s390x/stsi.c | 23 ++------------------
> 4 files changed, 91 insertions(+), 23 deletions(-)
> create mode 100644 lib/s390x/stsi.h
>
> diff --git a/lib/s390x/stsi.h b/lib/s390x/stsi.h
> new file mode 100644
> index 00000000..9b40664f
> --- /dev/null
> +++ b/lib/s390x/stsi.h
> @@ -0,0 +1,32 @@
> +/* SPDX-License-Identifier: GPL-2.0-or-later */
This was taken from stsi.c which is GPL 2 only, so this probably should
be as well.
> diff --git a/lib/s390x/vm.c b/lib/s390x/vm.c
> index a5b92863..38886b76 100644
> --- a/lib/s390x/vm.c
> +++ b/lib/s390x/vm.c
> @@ -12,6 +12,7 @@
> #include <alloc_page.h>
> #include <asm/arch_def.h>
> #include "vm.h"
> +#include "stsi.h"
>
> /**
> * Detect whether we are running with TCG (instead of KVM)
> @@ -26,9 +27,13 @@ bool vm_is_tcg(void)
> if (initialized)
> return is_tcg;
>
> - buf = alloc_page();
> - if (!buf)
> + if (!vm_is_vm()) {
> + initialized = true;
> return false;
> diff --git a/lib/s390x/vm.c b/lib/s390x/vm.c
> index a5b92863..38886b76 100644
> --- a/lib/s390x/vm.c
> +++ b/lib/s390x/vm.c
> @@ -12,6 +12,7 @@
> #include <alloc_page.h>
> #include <asm/arch_def.h>
> #include "vm.h"
> +#include "stsi.h"
>
> /**
> * Detect whether we are running with TCG (instead of KVM)
> @@ -26,9 +27,13 @@ bool vm_is_tcg(void)
> if (initialized)
> return is_tcg;
>
> - buf = alloc_page();
> - if (!buf)
> + if (!vm_is_vm()) {
> + initialized = true;
> return false;
I would personally prefer return is_tcg here to make it obvious we're
relying on the previous initalization to false for subsequent calls.
> + }
> +
> + buf = alloc_page();
> + assert(buf);
>
> if (stsi(buf, 1, 1, 1))
> goto out;
> @@ -43,3 +48,50 @@ out:
> free_page(buf);
> return is_tcg;
> }
> +
> +/**
> + * Detect whether we are running with KVM
> + */
> +
No newline here.
> +bool vm_is_kvm(void)
> +{
> + /* EBCDIC for "KVM/" */
> + const uint8_t kvm_ebcdic[] = { 0xd2, 0xe5, 0xd4, 0x61 };
> + static bool initialized;
> + static bool is_kvm;
Might make sense to initizalize these to false to make it consistent
with vm_is_tcg().
