Re: [kvm-unit-tests PATCH 1/5] lib: s390x: vm: Add kvm and lpar vm queries

[Janosch Frank <frankja@xxxxxxxxxxxxx>]

On 1/14/22 12:18, Claudio Imbrenda wrote:
> On Fri, 14 Jan 2022 10:02:41 +0000
> Janosch Frank <frankja@xxxxxxxxxxxxx> wrote:
>
> > This patch will likely (in parts) be replaced by Pierre's patch from
> > his topology test series.
> >
> > Signed-off-by: Janosch Frank <frankja@xxxxxxxxxxxxx>
>
> Reviewed-by: Claudio Imbrenda <imbrenda@xxxxxxxxxxxxx>
>
> although I think there is some room for improvement, but nothing too
> serious, I'll probably fix it myself later

I think I should add this to clean up the checks in the following patches:

bool vm_is_qemu(void)
{
	return vm_is_kvm() || vm_is_tcg();
}

That of course also isn't a 100% correct, we could have KVM + non-QEMU 
but I'll cross that bridge when I get there.

And as I already mentioned in Pierre's patch, the STSI values are a bit 
of a mystery to me since AFAIK we store KVM/Linux even if we run under TCG.

> > ---
> >   lib/s390x/vm.c | 39 +++++++++++++++++++++++++++++++++++++++
> >   lib/s390x/vm.h | 23 +++++++++++++++++++++++
> >   s390x/stsi.c   | 21 +--------------------
> >   3 files changed, 63 insertions(+), 20 deletions(-)
> >
> > diff --git a/lib/s390x/vm.c b/lib/s390x/vm.c
> > index a5b92863..266a81c1 100644
> > --- a/lib/s390x/vm.c
> > +++ b/lib/s390x/vm.c
> > @@ -26,6 +26,11 @@ bool vm_is_tcg(void)
> >   	if (initialized)
> >   		return is_tcg;
> >   
> > +	if (stsi_get_fc() < 3) {
> > +		initialized = true;
> > +		return false;
> > +	}
> > +
> >   	buf = alloc_page();
> >   	if (!buf)
> >   		return false;
> > @@ -43,3 +48,37 @@ out:
> >   	free_page(buf);
> >   	return is_tcg;
> >   }
> > +
> > +bool vm_is_kvm(void)
> > +{
> > +	const uint8_t cpi_kvm[] = { 0xd2, 0xe5, 0xd4, 0x61 };
> > +	struct stsi_322 *buf;
> > +	static bool initialized = false;
> > +	static bool is_kvm = false;
> > +
> > +	if (initialized)
> > +		return is_kvm;
> > +
> > +	if (stsi_get_fc() < 3) {
> > +		initialized = true;
> > +		return false;
> > +	}
> > +
> > +	buf = alloc_page();
> > +	if (!buf)
> > +		return false;
> > +
> > +	if (stsi(buf, 3, 2, 2))
> > +		goto out;
> > +
> > +	is_kvm = !(memcmp(&buf->vm[0].cpi, cpi_kvm, sizeof(cpi_kvm))) && !vm_is_tcg();
> > +	initialized = true;
> > +out:
> > +	free_page(buf);
> > +	return is_kvm;
> > +}
> > +
> > +bool vm_is_lpar(void)
> > +{
> > +	return stsi_get_fc() == 1;
> > +}
> > diff --git a/lib/s390x/vm.h b/lib/s390x/vm.h
> > index 7abba0cc..d4a82fc0 100644
> > --- a/lib/s390x/vm.h
> > +++ b/lib/s390x/vm.h
> > @@ -8,6 +8,29 @@
> >   #ifndef _S390X_VM_H_
> >   #define _S390X_VM_H_
> >   
> > +struct stsi_322 {
> > +	uint8_t reserved[31];
> > +	uint8_t count;
> > +	struct {
> > +		uint8_t reserved2[4];
> > +		uint16_t total_cpus;
> > +		uint16_t conf_cpus;
> > +		uint16_t standby_cpus;
> > +		uint16_t reserved_cpus;
> > +		uint8_t name[8];
> > +		uint32_t caf;
> > +		uint8_t cpi[16];
> > +		uint8_t reserved5[3];
> > +		uint8_t ext_name_encoding;
> > +		uint32_t reserved3;
> > +		uint8_t uuid[16];
> > +	} vm[8];
> > +	uint8_t reserved4[1504];
> > +	uint8_t ext_names[8][256];
> > +};
> > +
> >   bool vm_is_tcg(void);
> > +bool vm_is_kvm(void);
> > +bool vm_is_lpar(void);
> >   
> >   #endif  /* _S390X_VM_H_ */
> > diff --git a/s390x/stsi.c b/s390x/stsi.c
> > index 391f8849..e66d07a1 100644
> > --- a/s390x/stsi.c
> > +++ b/s390x/stsi.c
> > @@ -13,27 +13,8 @@
> >   #include <asm/asm-offsets.h>
> >   #include <asm/interrupt.h>
> >   #include <smp.h>
> > +#include <vm.h>
> >   
> > -struct stsi_322 {
> > -	uint8_t reserved[31];
> > -	uint8_t count;
> > -	struct {
> > -		uint8_t reserved2[4];
> > -		uint16_t total_cpus;
> > -		uint16_t conf_cpus;
> > -		uint16_t standby_cpus;
> > -		uint16_t reserved_cpus;
> > -		uint8_t name[8];
> > -		uint32_t caf;
> > -		uint8_t cpi[16];
> > -		uint8_t reserved5[3];
> > -		uint8_t ext_name_encoding;
> > -		uint32_t reserved3;
> > -		uint8_t uuid[16];
> > -	} vm[8];
> > -	uint8_t reserved4[1504];
> > -	uint8_t ext_names[8][256];
> > -};
> >   static uint8_t pagebuf[PAGE_SIZE * 2] __attribute__((aligned(PAGE_SIZE * 2)));
> >   
> >   static void test_specs(void)