From: Guo Ren <guoren@xxxxxxxxxxxxxxxxx> Force to enable virt_spin_lock when KVM guest, because fair locks have horrible lock 'holder' preemption issues. Suggested-by: Leonardo Bras <leobras@xxxxxxxxxx> Link: https://lkml.kernel.org/kvm/ZQK9-tn2MepXlY1u@xxxxxxxxxx/ Signed-off-by: Guo Ren <guoren@xxxxxxxxxxxxxxxxx> Signed-off-by: Guo Ren <guoren@xxxxxxxxxx> --- arch/riscv/include/asm/sbi.h | 8 ++++++++ arch/riscv/kernel/sbi.c | 2 +- arch/riscv/kernel/setup.c | 6 +++++- 3 files changed, 14 insertions(+), 2 deletions(-) diff --git a/arch/riscv/include/asm/sbi.h b/arch/riscv/include/asm/sbi.h index 0892f4421bc4..8f748d9e1b85 100644 --- a/arch/riscv/include/asm/sbi.h +++ b/arch/riscv/include/asm/sbi.h @@ -51,6 +51,13 @@ enum sbi_ext_base_fid { SBI_EXT_BASE_GET_MIMPID, }; +enum sbi_ext_base_impl_id { + SBI_EXT_BASE_IMPL_ID_BBL = 0, + SBI_EXT_BASE_IMPL_ID_OPENSBI, + SBI_EXT_BASE_IMPL_ID_XVISOR, + SBI_EXT_BASE_IMPL_ID_KVM, +}; + enum sbi_ext_time_fid { SBI_EXT_TIME_SET_TIMER = 0, }; @@ -276,6 +283,7 @@ int sbi_console_getchar(void); long sbi_get_mvendorid(void); long sbi_get_marchid(void); long sbi_get_mimpid(void); +long sbi_get_firmware_id(void); void sbi_set_timer(uint64_t stime_value); void sbi_shutdown(void); void sbi_send_ipi(unsigned int cpu); diff --git a/arch/riscv/kernel/sbi.c b/arch/riscv/kernel/sbi.c index 5a62ed1da453..4330aedf65fd 100644 --- a/arch/riscv/kernel/sbi.c +++ b/arch/riscv/kernel/sbi.c @@ -543,7 +543,7 @@ static inline long sbi_get_spec_version(void) return __sbi_base_ecall(SBI_EXT_BASE_GET_SPEC_VERSION); } -static inline long sbi_get_firmware_id(void) +long sbi_get_firmware_id(void) { return __sbi_base_ecall(SBI_EXT_BASE_GET_IMP_ID); } diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c index 0bafb9fd6ea3..e33430e9d97e 100644 --- a/arch/riscv/kernel/setup.c +++ b/arch/riscv/kernel/setup.c @@ -281,6 +281,9 @@ DEFINE_STATIC_KEY_TRUE(virt_spin_lock_key); static void __init virt_spin_lock_init(void) { + if (sbi_get_firmware_id() != SBI_EXT_BASE_IMPL_ID_KVM) + no_virt_spin = true; + if (no_virt_spin) static_branch_disable(&virt_spin_lock_key); else @@ -290,7 +293,8 @@ static void __init virt_spin_lock_init(void) static void __init riscv_spinlock_init(void) { - if (!enable_qspinlock) { + if ((!enable_qspinlock) && + (sbi_get_firmware_id() != SBI_EXT_BASE_IMPL_ID_KVM)) { static_branch_disable(&combo_qspinlock_key); pr_info("Ticket spinlock: enabled\n"); } else { -- 2.40.1
