Re: [kvm-unit-tests PATCH 1/1] s390x: stsi: Define vm_is_kvm to be used in different tests

[Pierre Morel <pmorel@xxxxxxxxxxxxx>]

On 2/15/22 16:21, Claudio Imbrenda wrote:
> On Tue, 15 Feb 2022 16:08:16 +0100
> Janosch Frank <frankja@xxxxxxxxxxxxx> wrote:
>
> > On 2/15/22 13:06, Claudio Imbrenda wrote:
> > > On Tue, 15 Feb 2022 11:46:32 +0100
> > > Pierre Morel <pmorel@xxxxxxxxxxxxx> wrote:
> > >    
> > > > Several tests are in need of a way to check on which hypervisor
> > > > and virtualization level they are running on to be able to fence
> > > > certain tests. This patch adds functions that return true if a
> > > > vm is running under KVM, LPAR or generally as a level 2 guest.
> > > >
> > > > To check if we're running under KVM we use the STSI 3.2.2
> > > > instruction, let's define it's response structure in a central
> > > > header.
> > > >   
> > >
> > > sorry, I had replied to the old series, let me reply here too
> > >
> > >
> > > I think it would look cleaner if there was only one
> > > "detect_environment" function, that would call stsi once and detect the
> > > environment, then the various vm_is_* would become something like
> > >
> > > bool vm_is_*(void)
> > > {
> > > 	return detect_environment() == VM_IS_*;
> > > }
> > >
> > > of course detect_environment would also cache the result with static
> > > variables.
> > >
> > > bonus, we could make that function public, so a testcase could just
> > > switch over the type of hypervisor it's being run on, instead of having
> > > to use a series of ifs.
> > >
> > > and then maybe the various vm_is_* could become static inlines to be put
> > > in the header.
> > >
> > > please note that "detect_environment" is just the first thing that came
> > > to my mind, I have no preference regarding the name.
> >
> > I'd like to keep this patch as simple as possible because there are
> > multiple patch sets which are gated by it.
> >
> > The vm.h code and the skey.c z/VM 6 check is a thorn in my side anyway
> > and I'd rather have it fixed properly which will likely result in a lot
> > of opinions being voiced.
> >
> > So I'd propose to rename vm_is_vm() to vm_is_guest2() and pick this patch.
>
> ok for me
>
> I'll rename the function and queue the patch

Not OK for me, in the POP PTF do not do any difference between guest 2 
and guest 3.

Or do you want to implement a VSIE specificity ?


> > >    
> > > > Signed-off-by: Pierre Morel <pmorel@xxxxxxxxxxxxx>
> > > > ---
> > > >    lib/s390x/stsi.h | 32 ++++++++++++++++++++++++++++
> > > >    lib/s390x/vm.c   | 55 ++++++++++++++++++++++++++++++++++++++++++++++--
> > > >    lib/s390x/vm.h   |  3 +++
> > > >    s390x/stsi.c     | 23 ++------------------
> > > >    4 files changed, 90 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..bebc492d
> > > > --- /dev/null
> > > > +++ b/lib/s390x/stsi.h
> > > > @@ -0,0 +1,32 @@
> > > > +/* SPDX-License-Identifier: GPL-2.0-only */
> > > > +/*
> > > > + * Structures used to Store System Information
> > > > + *
> > > > + * Copyright IBM Corp. 2022
> > > > + */
> > > > +
> > > > +#ifndef _S390X_STSI_H_
> > > > +#define _S390X_STSI_H_
> > > > +
> > > > +struct sysinfo_3_2_2 {
> > > > +	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];
> > > > +};
> > > > +
> > > > +#endif  /* _S390X_STSI_H_ */
> > > > diff --git a/lib/s390x/vm.c b/lib/s390x/vm.c
> > > > index a5b92863..91acd05b 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;
> > > >    
> > > > +	if (!vm_is_vm()) {
> > > > +		initialized = true;
> > > > +		return is_tcg;
> > > > +	}
> > > > +
> > > >    	buf = alloc_page();
> > > > -	if (!buf)
> > > > -		return false;
> > > > +	assert(buf);
> > > >    
> > > >    	if (stsi(buf, 1, 1, 1))
> > > >    		goto out;
> > > > @@ -43,3 +48,49 @@ out:
> > > >    	free_page(buf);
> > > >    	return is_tcg;
> > > >    }
> > > > +
> > > > +/**
> > > > + * Detect whether we are running with KVM
> > > > + */
> > > > +bool vm_is_kvm(void)
> > > > +{
> > > > +	/* EBCDIC for "KVM/" */
> > > > +	const uint8_t kvm_ebcdic[] = { 0xd2, 0xe5, 0xd4, 0x61 };
> > > > +	static bool initialized;
> > > > +	static bool is_kvm;
> > > > +	struct sysinfo_3_2_2 *stsi_322;
> > > > +
> > > > +	if (initialized)
> > > > +		return is_kvm;
> > > > +
> > > > +	if (!vm_is_vm() || vm_is_tcg()) {
> > > > +		initialized = true;
> > > > +		return is_kvm;
> > > > +	}
> > > > +
> > > > +	stsi_322 = alloc_page();
> > > > +	assert(stsi_322);
> > > > +
> > > > +	if (stsi(stsi_322, 3, 2, 2))
> > > > +		goto out;
> > > > +
> > > > +	/*
> > > > +	 * If the manufacturer string is "KVM/" in EBCDIC, then we
> > > > +	 * are on KVM.
> > > > +	 */
> > > > +	is_kvm = !memcmp(&stsi_322->vm[0].cpi, kvm_ebcdic, sizeof(kvm_ebcdic));
> > > > +	initialized = true;
> > > > +out:
> > > > +	free_page(stsi_322);
> > > > +	return is_kvm;
> > > > +}
> > > > +
> > > > +bool vm_is_lpar(void)
> > > > +{
> > > > +	return stsi_get_fc() == 2;
> > > > +}
> > > > +
> > > > +bool vm_is_vm(void)
> > > > +{
> > > > +	return stsi_get_fc() == 3;
> > > > +}
> > > > diff --git a/lib/s390x/vm.h b/lib/s390x/vm.h
> > > > index 7abba0cc..3aaf76af 100644
> > > > --- a/lib/s390x/vm.h
> > > > +++ b/lib/s390x/vm.h
> > > > @@ -9,5 +9,8 @@
> > > >    #define _S390X_VM_H_
> > > >    
> > > >    bool vm_is_tcg(void);
> > > > +bool vm_is_kvm(void);
> > > > +bool vm_is_vm(void);
> > > > +bool vm_is_lpar(void);
> > > >    
> > > >    #endif  /* _S390X_VM_H_ */
> > > > diff --git a/s390x/stsi.c b/s390x/stsi.c
> > > > index 391f8849..dccc53e7 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 <stsi.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)
> > > > @@ -91,7 +72,7 @@ static void test_3_2_2(void)
> > > >    	/* EBCDIC for "KVM/" */
> > > >    	const uint8_t cpi_kvm[] = { 0xd2, 0xe5, 0xd4, 0x61 };
> > > >    	const char vm_name_ext[] = "kvm-unit-test";
> > > > -	struct stsi_322 *data = (void *)pagebuf;
> > > > +	struct sysinfo_3_2_2 *data = (void *)pagebuf;
> > > >    
> > > >    	report_prefix_push("3.2.2");
> > > >      
> > >    

--
Pierre Morel
IBM Lab Boeblingen