From mboxrd@z Thu Jan  1 00:00:00 1970
From: Sergey Matyukevich <geomatsi@gmail.com>
Date: Wed, 9 Nov 2022 16:42:27 +0300
Subject: [RFC  4/9] RISC-V: KVM: Improve privilege mode filtering for perf
In-Reply-To: <20220718170205.2972215-5-atishp@rivosinc.com>
References: <20220718170205.2972215-1-atishp@rivosinc.com>
 <20220718170205.2972215-5-atishp@rivosinc.com>
Message-ID: <Y2uuQ4wH4dU98K2b@curiosity>
List-Id: <kvm-riscv.lists.infradead.org>
To: kvm-riscv@lists.infradead.org
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Hi Atish,

> Currently, the host driver doesn't have any method to identify if the
> requested perf event is from kvm or bare metal. As KVM runs in HS
> mode, there are no separate hypervisor privilege mode to distinguish
> between the attributes for guest/host.
> 
> Improve the privilege mode filtering by using the event specific
> config1 field.

... [snip]

> +static unsigned long pmu_sbi_get_filter_flags(struct perf_event *event)
> +{
> +	unsigned long cflags = 0;
> +	bool guest_events = false;
> +
> +	if (event->attr.config1 & RISCV_KVM_PMU_CONFIG1_GUEST_EVENTS)
> +		guest_events = true;
> +	if (event->attr.exclude_kernel)
> +		cflags |= guest_events ? SBI_PMU_CFG_FLAG_SET_VSINH : SBI_PMU_CFG_FLAG_SET_SINH;

IIUC we should inhibit host counting if we want guest events:
		cflags |= guest_events ? SBI_PMU_CFG_FLAG_SET_SINH : SBI_PMU_CFG_FLAG_SET_VSINH;

> +	if (event->attr.exclude_user)
> +		cflags |= guest_events ? SBI_PMU_CFG_FLAG_SET_VUINH : SBI_PMU_CFG_FLAG_SET_UINH;

Same here.

> +	if (guest_events && event->attr.exclude_hv)
> +		cflags |= SBI_PMU_CFG_FLAG_SET_SINH;
> +	if (event->attr.exclude_host)
> +		cflags |= SBI_PMU_CFG_FLAG_SET_UINH | SBI_PMU_CFG_FLAG_SET_SINH;
> +	if (event->attr.exclude_guest)
> +		cflags |= SBI_PMU_CFG_FLAG_SET_VSINH | SBI_PMU_CFG_FLAG_SET_VUINH;
> +
> +	return cflags;
> +}

Regards,
Sergey