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[58.6.239.121]) by smtp.gmail.com with ESMTPSA id a9sm5925868pjq.17.2021.02.25.05.48.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 25 Feb 2021 05:48:04 -0800 (PST) From: Nicholas Piggin To: kvm-ppc@vger.kernel.org Subject: [PATCH v2 18/37] KVM: PPC: Book3S HV P9: Use large decrementer for HDEC Date: Thu, 25 Feb 2021 23:46:33 +1000 Message-Id: <20210225134652.2127648-19-npiggin@gmail.com> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20210225134652.2127648-1-npiggin@gmail.com> References: <20210225134652.2127648-1-npiggin@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linuxppc-dev@lists.ozlabs.org, Nicholas Piggin Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" 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. 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 63cc92c45c5d..913582bd848f 100644 --- a/arch/powerpc/kvm/book3s_hv.c +++ b/arch/powerpc/kvm/book3s_hv.c @@ -3609,7 +3609,8 @@ 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