Rename the function to indicate that it is meant for firmware
counter read. While at it, add a range sanity check for it as
well.
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Atish Patra <atishp@rivosinc.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/r/20240420151741.962500-17-atishp@rivosinc.com
Signed-off-by: Anup Patel <anup@brainfault.org>
The SBI v2.0 introduced a fw_read_hi function to read 64 bit firmware
counters for RV32 based systems.
Add infrastructure to support that.
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Signed-off-by: Atish Patra <atishp@rivosinc.com>
Link: https://lore.kernel.org/r/20240420151741.962500-16-atishp@rivosinc.com
Signed-off-by: Anup Patel <anup@brainfault.org>
KVM enables perf for guest via counter virtualization. However, the
sampling can not be supported as there is no mechanism to enabled
trap/emulate scountovf in ISA yet. Rely on the SBI PMU snapshot
to provide the counter overflow data via the shared memory.
In case of sampling event, the host first sets the guest's LCOFI
interrupt and injects to the guest via irq filtering mechanism defined
in AIA specification. Thus, ssaia must be enabled in the host in order
to use perf sampling in the guest. No other AIA dependency w.r.t kernel
is required.
Reviewed-by: Anup Patel <anup@brainfault.org>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Atish Patra <atishp@rivosinc.com>
Link: https://lore.kernel.org/r/20240420151741.962500-15-atishp@rivosinc.com
Signed-off-by: Anup Patel <anup@brainfault.org>
PMU Snapshot function allows to minimize the number of traps when the
guest access configures/access the hpmcounters. If the snapshot feature
is enabled, the hypervisor updates the shared memory with counter
data and state of overflown counters. The guest can just read the
shared memory instead of trap & emulate done by the hypervisor.
This patch doesn't implement the counter overflow yet.
Reviewed-by: Anup Patel <anup@brainfault.org>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Atish Patra <atishp@rivosinc.com>
Link: https://lore.kernel.org/r/20240420151741.962500-14-atishp@rivosinc.com
Signed-off-by: Anup Patel <anup@brainfault.org>
Currently, we return a linux error code if creating a perf event failed
in kvm. That shouldn't be necessary as guest can continue to operate
without perf profiling or profiling with firmware counters.
Return appropriate SBI error code to indicate that PMU configuration
failed. An error message in kvm already describes the reason for failure.
Fixes: 0cb74b65d2 ("RISC-V: KVM: Implement perf support without sampling")
Reviewed-by: Anup Patel <anup@brainfault.org>
Signed-off-by: Atish Patra <atishp@rivosinc.com>
Link: https://lore.kernel.org/r/20240420151741.962500-13-atishp@rivosinc.com
Signed-off-by: Anup Patel <anup@brainfault.org>
The virtual counter value is updated during pmu_ctr_read. There is no need
to update it in reset case. Otherwise, it will be counted twice which is
incorrect.
Fixes: 0cb74b65d2 ("RISC-V: KVM: Implement perf support without sampling")
Reviewed-by: Anup Patel <anup@brainfault.org>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Atish Patra <atishp@rivosinc.com>
Link: https://lore.kernel.org/r/20240420151741.962500-12-atishp@rivosinc.com
Signed-off-by: Anup Patel <anup@brainfault.org>
The initial sample period value when counter value is not assigned
should be set to maximum value supported by the counter width.
Otherwise, it may result in spurious interrupts.
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Atish Patra <atishp@rivosinc.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/r/20240420151741.962500-11-atishp@rivosinc.com
Signed-off-by: Anup Patel <anup@brainfault.org>
SBI PMU extension defines a set of firmware events which can provide
useful information to guests about the number of SBI calls. As
hypervisor implements the SBI PMU extension, these firmware events
correspond to ecall invocations between VS->HS mode. All other firmware
events will always report zero if monitored as KVM doesn't implement them.
This patch adds all the infrastructure required to support firmware
events.
Reviewed-by: Anup Patel <anup@brainfault.org>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Atish Patra <atishp@rivosinc.com>
Signed-off-by: Anup Patel <anup@brainfault.org>
RISC-V SBI PMU & Sscofpmf ISA extension allows supporting perf in
the virtualization enviornment as well. KVM implementation
relies on SBI PMU extension for the most part while trapping
& emulating the CSRs read for counter access.
This patch doesn't have the event sampling support yet.
Reviewed-by: Anup Patel <anup@brainfault.org>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Atish Patra <atishp@rivosinc.com>
Signed-off-by: Anup Patel <anup@brainfault.org>
As the KVM guests only see the virtual PMU counters, all hpmcounter
access should trap and KVM emulates the read access on behalf of guests.
Reviewed-by: Anup Patel <anup@brainfault.org>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Atish Patra <atishp@rivosinc.com>
Signed-off-by: Anup Patel <anup@brainfault.org>
The privilege mode filtering feature must be available in the host so
that the host can inhibit the counters while the execution is in HS mode.
Otherwise, the guests may have access to critical guest information.
Reviewed-by: Anup Patel <anup@brainfault.org>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Atish Patra <atishp@rivosinc.com>
Signed-off-by: Anup Patel <anup@brainfault.org>
This patch only adds barebone structure of perf implementation. Most
of the function returns zero at this point and will be implemented
fully in the future.
Reviewed-by: Anup Patel <anup@brainfault.org>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Atish Patra <atishp@rivosinc.com>
Signed-off-by: Anup Patel <anup@brainfault.org>
