On Tue, May 30, 2023, Jinrong Liang wrote:
> From: Jinrong Liang <cloudliang@xxxxxxxxxxx>
>
> To introduce a new pmu.h header file under
> tools/testing/selftests/kvm/include/x86_64 directory to better
> organize the PMU performance event constants and common masks.
> It will enhance the maintainability and readability of the KVM
> selftests code.
>
> In the new pmu.h header, to define the PMU performance events and
> masks that are relevant for x86_64, allowing developers to easily
> reference them and minimize potential errors in code that handles
> these values.
Same feedback as the previous changelog.
> Signed-off-by: Jinrong Liang <cloudliang@xxxxxxxxxxx>
> ---
> .../selftests/kvm/include/x86_64/pmu.h | 56 +++++++++++++++++++
> 1 file changed, 56 insertions(+)
> create mode 100644 tools/testing/selftests/kvm/include/x86_64/pmu.h
>
> diff --git a/tools/testing/selftests/kvm/include/x86_64/pmu.h b/tools/testing/selftests/kvm/include/x86_64/pmu.h
> new file mode 100644
> index 000000000000..0e0111b11024
> --- /dev/null
> +++ b/tools/testing/selftests/kvm/include/x86_64/pmu.h
> @@ -0,0 +1,56 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * tools/testing/selftests/kvm/include/x86_64/pmu.h
> + *
> + * Copyright (C) 2023, Tencent, Inc.
> + */
> +#ifndef _PMU_H_
> +#define _PMU_H_
SELFTEST_KVM_PMU_H for consistency, and to minimize the risk of a collision.
> +#include "processor.h"
> +
> +#define GP_CTR_NUM_OFS_BIT 8
> +#define EVT_LEN_OFS_BIT 24
Please spell out the words, I genuinely have no idea what these refer to, and
readers shouldn't have to consult the SDM just to understand a name.
> +#define INTEL_PMC_IDX_FIXED 32
> +
> +#define PMU_CAP_FW_WRITES BIT_ULL(13)
> +#define EVENTSEL_OS BIT_ULL(17)
> +#define EVENTSEL_ANY BIT_ULL(21)
> +#define EVENTSEL_EN BIT_ULL(22)
> +#define RDPMC_FIXED_BASE BIT_ULL(30)
> +
> +#define PMU_VERSION_MASK GENMASK_ULL(7, 0)
> +#define EVENTS_MASK GENMASK_ULL(7, 0)
> +#define EVT_LEN_MASK GENMASK_ULL(31, EVT_LEN_OFS_BIT)
> +#define GP_CTR_NUM_MASK GENMASK_ULL(15, GP_CTR_NUM_OFS_BIT)
> +#define FIXED_CTR_NUM_MASK GENMASK_ULL(4, 0)
> +
> +#define X86_INTEL_PMU_VERSION kvm_cpu_property(X86_PROPERTY_PMU_VERSION)
> +#define X86_INTEL_MAX_GP_CTR_NUM kvm_cpu_property(X86_PROPERTY_PMU_NR_GP_COUNTERS)
> +#define X86_INTEL_MAX_FIXED_CTR_NUM kvm_cpu_property(X86_PROPERTY_PMU_NR_FIXED_COUNTERS)
> +#define X86_INTEL_FIXED_CTRS_BITMASK kvm_cpu_property(X86_PROPERTY_PMU_FIXED_CTRS_BITMASK)
Please don't add macros like this. It gives the false impression that all these
values are constant at compile time, which is very much not the case. I really,
really dislike code that hides important details, like the fact that this is
querying KVM.
Yeah, the line lengths will be longer, but 80 chars is a soft limit, and we can
always get creative, e.g.
uint8_t max_pmu_version = kvm_cpu_property(X86_PROPERTY_PMU_VERSION);
struct kvm_vm *vm;
struct kvm_vcpu *vcpu;
uint8_t version;
TEST_REQUIRE(kvm_cpu_property(X86_PROPERTY_PMU_NR_FIXED_COUNTERS) > 2);
> +/* Definitions for Architectural Performance Events */
> +#define ARCH_EVENT(select, umask) (((select) & 0xff) | ((umask) & 0xff) << 8)
> +
> +/* Intel Pre-defined Architectural Performance Events */
> +static const uint64_t arch_events[] = {
> + [0] = ARCH_EVENT(0x3c, 0x0),
> + [1] = ARCH_EVENT(0xc0, 0x0),
> + [2] = ARCH_EVENT(0x3c, 0x1),
> + [3] = ARCH_EVENT(0x2e, 0x4f),
> + [4] = ARCH_EVENT(0x2e, 0x41),
> + [5] = ARCH_EVENT(0xc4, 0x0),
> + [6] = ARCH_EVENT(0xc5, 0x0),
> + [7] = ARCH_EVENT(0xa4, 0x1),
Please do something like I proposed for KVM, i.e. avoid magic numbers inasmuch
as possible.
https://lore.kernel.org/all/20230607010206.1425277-2-seanjc@xxxxxxxxxx
> +};
> +
> +/* Association of Fixed Counters with Architectural Performance Events */
> +static int fixed_events[] = {1, 0, 7};
> +
> +static inline uint64_t evt_code_for_fixed_ctr(uint8_t idx)
s/evt/event. Having consistent naming is more important than saving two characters.
> +{
> + return arch_events[fixed_events[idx]];
> +}
> +
> +#endif /* _PMU_H_ */
> --
> 2.31.1
>
