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

[Claudio Imbrenda <imbrenda@linux.ibm.com>]

On Tue, 15 Feb 2022 16:08:16 +0100
Janosch Frank <frankja@linux.ibm.com> wrote:

> On 2/15/22 13:06, Claudio Imbrenda wrote:
> > On Tue, 15 Feb 2022 11:46:32 +0100
> > Pierre Morel <pmorel@linux.ibm.com> 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

> 
> >   
> >> Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
> >> ---
> >>   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");
> >>     
> >   
>