From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nicholas Piggin Date: Tue, 23 Mar 2021 01:02:43 +0000 Subject: [PATCH v4 24/46] KVM: PPC: Book3S HV P9: Use large decrementer for HDEC Message-Id: <20210323010305.1045293-25-npiggin@gmail.com> List-Id: References: <20210323010305.1045293-1-npiggin@gmail.com> In-Reply-To: <20210323010305.1045293-1-npiggin@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: kvm-ppc@vger.kernel.org Cc: Alexey Kardashevskiy , linuxppc-dev@lists.ozlabs.org, Nicholas Piggin On processors that don't suppress the HDEC exceptions when LPCR[HDICE]=0, this could help reduce needless guest exits due to leftover exceptions on entering the guest. Reviewed-by: Alexey Kardashevskiy Signed-off-by: Nicholas Piggin --- arch/powerpc/include/asm/time.h | 2 ++ arch/powerpc/kvm/book3s_hv.c | 3 ++- 2 files changed, 4 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/include/asm/time.h b/arch/powerpc/include/asm/time.h index 8dd3cdb25338..68d94711811e 100644 --- a/arch/powerpc/include/asm/time.h +++ b/arch/powerpc/include/asm/time.h @@ -18,6 +18,8 @@ #include /* time.c */ +extern u64 decrementer_max; + extern unsigned long tb_ticks_per_jiffy; extern unsigned long tb_ticks_per_usec; extern unsigned long tb_ticks_per_sec; diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c index 8215430e6d5e..bb30c5ab53d1 100644 --- a/arch/powerpc/kvm/book3s_hv.c +++ b/arch/powerpc/kvm/book3s_hv.c @@ -3658,7 +3658,8 @@ static int kvmhv_load_hv_regs_and_go(struct kvm_vcpu *vcpu, u64 time_limit, vc->tb_offset_applied = 0; } - mtspr(SPRN_HDEC, 0x7fffffff); + /* HDEC must be at least as large as DEC, so decrementer_max fits */ + mtspr(SPRN_HDEC, decrementer_max); switch_mmu_to_host_radix(kvm, host_pidr); -- 2.23.0