[PATCH v12 03/21] KVM: ARM64: Add offset defines for PMU registers
From: Marc Zyngier <hidden>
Date: 2016-02-22 17:51:20
Also in:
kvm, kvmarm
On 22/02/16 09:37, Shannon Zhao wrote:
quoted hunk ↗ jump to hunk
From: Shannon Zhao <redacted> We are about to trap and emulate accesses to each PMU register individually. This adds the context offsets for the AArch64 PMU registers. Signed-off-by: Shannon Zhao <redacted> Reviewed-by: Marc Zyngier <redacted> Reviewed-by: Andrew Jones <redacted> --- arch/arm64/include/asm/kvm_host.h | 15 +++++++++++++++ 1 file changed, 15 insertions(+)diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index 6f0241f..6bab7fb 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h@@ -115,6 +115,21 @@ enum vcpu_sysreg { MDSCR_EL1, /* Monitor Debug System Control Register */ MDCCINT_EL1, /* Monitor Debug Comms Channel Interrupt Enable Reg */ + /* Performance Monitors Registers */ + PMCR_EL0, /* Control Register */ + PMOVSSET_EL0, /* Overflow Flag Status Set Register */ + PMSELR_EL0, /* Event Counter Selection Register */ + PMEVCNTR0_EL0, /* Event Counter Register (0-30) */ + PMEVCNTR30_EL0 = PMEVCNTR0_EL0 + 30, + PMCCNTR_EL0, /* Cycle Counter Register */ + PMEVTYPER0_EL0, /* Event Type Register (0-30) */ + PMEVTYPER30_EL0 = PMEVTYPER0_EL0 + 30, + PMCCFILTR_EL0, /* Cycle Count Filter Register */ + PMCNTENSET_EL0, /* Count Enable Set Register */ + PMINTENSET_EL1, /* Interrupt Enable Set Register */ + PMUSERENR_EL0, /* User Enable Register */ + PMSWINC_EL0, /* Software Increment Register */ +
I've just noticed a rather fundamental issue with this: this makes it impossible to bisect the whole series. I was trying to pinpoint a performance regression with this series, and started bisecting. Unfortunately, declaring these registers in one go means that we end-up with uninitialized registers after this patch (and probably until PMUSERENR is dealt with). The consequence of that is something like this: Kernel panic - not syncing: Didn't reset vcpu_sys_reg(25) CPU: 1 PID: 1994 Comm: lkvm Tainted: G W 4.5.0-rc5+ #5563 Hardware name: Default string Default string/Default string, BIOS ROD0084E 09/03/2015 Call trace: [<ffffffc000089a20>] dump_backtrace+0x0/0x1a8 [<ffffffc000089bdc>] show_stack+0x14/0x20 [<ffffffc00033490c>] dump_stack+0x94/0xb8 [<ffffffc00014ddbc>] panic+0x10c/0x250 [<ffffffc0000a9c94>] kvm_reset_sys_regs+0xec/0xf0 [<ffffffc0000a7878>] kvm_reset_vcpu+0x58/0x80 [<ffffffc0000a2c44>] kvm_arch_vcpu_ioctl+0x294/0x310 [<ffffffc00009d6b4>] kvm_vcpu_ioctl+0xcc/0x698 [<ffffffc0001cb184>] do_vfs_ioctl+0xa4/0x750 [<ffffffc0001cb8bc>] SyS_ioctl+0x8c/0xa0 [<ffffffc000085d30>] el0_svc_naked+0x24/0x28 The obvious fix would be to introduce each register with the patch that handles it. At least, we'll be able to bisect it... Thanks, M. -- Jazz is not dead. It just smells funny...