From: James Hogan <james.hogan@imgtec.com> To: <linux-mips@linux-mips.org>, <kvm@vger.kernel.org> Cc: "James Hogan" <james.hogan@imgtec.com>, "Paolo Bonzini" <pbonzini@redhat.com>, "Radim Krčmář" <rkrcmar@redhat.com>, "Ralf Baechle" <ralf@linux-mips.org> Subject: [PATCH v2 21/33] KVM: MIPS/Emulate: Update CP0_Compare emulation for VZ Date: Tue, 14 Mar 2017 10:15:28 +0000 [thread overview] Message-ID: <eb8eaf283cea07b0a59ce0acd8db6544ae7c1877.1489485940.git-series.james.hogan@imgtec.com> (raw) In-Reply-To: <cover.26e10ec77a4ed0d3177ccf4fabf57bc95ea030f8.1489485940.git-series.james.hogan@imgtec.com> Update emulation of guest writes to CP0_Compare for VZ. There are two main differences compared to trap & emulate: - Writing to CP0_Compare in the VZ hardware guest context acks any pending timer, clearing CP0_Cause.TI. If we don't want an ack to take place we must carefully restore the TI bit if it was previously set. - Even with guest timer access disabled in CP0_GuestCtl0.GT, if the guest CP0_Count reaches the guest CP0_Compare the timer interrupt will assert. To prevent this we must set CP0_GTOffset to move the guest CP0_Count out of the way of the new guest CP0_Compare, either before or after depending on whether it is a forwards or backwards change. Signed-off-by: James Hogan <james.hogan@imgtec.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: "Radim Krčmář" <rkrcmar@redhat.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: linux-mips@linux-mips.org Cc: kvm@vger.kernel.org --- arch/mips/kvm/emulate.c | 43 +++++++++++++++++++++++++++++++++++++++++- 1 file changed, 42 insertions(+), 1 deletion(-) diff --git a/arch/mips/kvm/emulate.c b/arch/mips/kvm/emulate.c index e6fce30eb440..42424822898c 100644 --- a/arch/mips/kvm/emulate.c +++ b/arch/mips/kvm/emulate.c @@ -621,7 +621,9 @@ void kvm_mips_write_compare(struct kvm_vcpu *vcpu, u32 compare, bool ack) struct mips_coproc *cop0 = vcpu->arch.cop0; int dc; u32 old_compare = kvm_read_c0_guest_compare(cop0); - ktime_t now; + s32 delta = compare - old_compare; + u32 cause; + ktime_t now = ktime_set(0, 0); /* silence bogus GCC warning */ u32 count; /* if unchanged, must just be an ack */ @@ -633,6 +635,21 @@ void kvm_mips_write_compare(struct kvm_vcpu *vcpu, u32 compare, bool ack) return; } + /* + * If guest CP0_Compare moves forward, CP0_GTOffset should be adjusted + * too to prevent guest CP0_Count hitting guest CP0_Compare. + * + * The new GTOffset corresponds to the new value of CP0_Compare, and is + * set prior to it being written into the guest context. We disable + * preemption until the new value is written to prevent restore of a + * GTOffset corresponding to the old CP0_Compare value. + */ + if (IS_ENABLED(CONFIG_KVM_MIPS_VZ) && delta > 0) { + preempt_disable(); + write_c0_gtoffset(compare - read_c0_count()); + back_to_back_c0_hazard(); + } + /* freeze_hrtimer() takes care of timer interrupts <= count */ dc = kvm_mips_count_disabled(vcpu); if (!dc) @@ -640,12 +657,36 @@ void kvm_mips_write_compare(struct kvm_vcpu *vcpu, u32 compare, bool ack) if (ack) kvm_mips_callbacks->dequeue_timer_int(vcpu); + else if (IS_ENABLED(CONFIG_KVM_MIPS_VZ)) + /* + * With VZ, writing CP0_Compare acks (clears) CP0_Cause.TI, so + * preserve guest CP0_Cause.TI if we don't want to ack it. + */ + cause = kvm_read_c0_guest_cause(cop0); kvm_write_c0_guest_compare(cop0, compare); + if (IS_ENABLED(CONFIG_KVM_MIPS_VZ)) { + if (delta > 0) + preempt_enable(); + + back_to_back_c0_hazard(); + + if (!ack && cause & CAUSEF_TI) + kvm_write_c0_guest_cause(cop0, cause); + } + /* resume_hrtimer() takes care of timer interrupts > count */ if (!dc) kvm_mips_resume_hrtimer(vcpu, now, count); + + /* + * If guest CP0_Compare is moving backward, we delay CP0_GTOffset change + * until after the new CP0_Compare is written, otherwise new guest + * CP0_Count could hit new guest CP0_Compare. + */ + if (IS_ENABLED(CONFIG_KVM_MIPS_VZ) && delta <= 0) + write_c0_gtoffset(compare - read_c0_count()); } /** -- git-series 0.8.10
WARNING: multiple messages have this Message-ID (diff)
From: James Hogan <james.hogan@imgtec.com> To: linux-mips@linux-mips.org, kvm@vger.kernel.org Cc: "James Hogan" <james.hogan@imgtec.com>, "Paolo Bonzini" <pbonzini@redhat.com>, "Radim Krčmář" <rkrcmar@redhat.com>, "Ralf Baechle" <ralf@linux-mips.org> Subject: [PATCH v2 21/33] KVM: MIPS/Emulate: Update CP0_Compare emulation for VZ Date: Tue, 14 Mar 2017 10:15:28 +0000 [thread overview] Message-ID: <eb8eaf283cea07b0a59ce0acd8db6544ae7c1877.1489485940.git-series.james.hogan@imgtec.com> (raw) Message-ID: <20170314101528.KzH9mNc4QGR44KlJx-nq3cjHIBHnGAa4rsZMH0WSMwE@z> (raw) In-Reply-To: <cover.26e10ec77a4ed0d3177ccf4fabf57bc95ea030f8.1489485940.git-series.james.hogan@imgtec.com> Update emulation of guest writes to CP0_Compare for VZ. There are two main differences compared to trap & emulate: - Writing to CP0_Compare in the VZ hardware guest context acks any pending timer, clearing CP0_Cause.TI. If we don't want an ack to take place we must carefully restore the TI bit if it was previously set. - Even with guest timer access disabled in CP0_GuestCtl0.GT, if the guest CP0_Count reaches the guest CP0_Compare the timer interrupt will assert. To prevent this we must set CP0_GTOffset to move the guest CP0_Count out of the way of the new guest CP0_Compare, either before or after depending on whether it is a forwards or backwards change. Signed-off-by: James Hogan <james.hogan@imgtec.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: "Radim Krčmář" <rkrcmar@redhat.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: linux-mips@linux-mips.org Cc: kvm@vger.kernel.org --- arch/mips/kvm/emulate.c | 43 +++++++++++++++++++++++++++++++++++++++++- 1 file changed, 42 insertions(+), 1 deletion(-) diff --git a/arch/mips/kvm/emulate.c b/arch/mips/kvm/emulate.c index e6fce30eb440..42424822898c 100644 --- a/arch/mips/kvm/emulate.c +++ b/arch/mips/kvm/emulate.c @@ -621,7 +621,9 @@ void kvm_mips_write_compare(struct kvm_vcpu *vcpu, u32 compare, bool ack) struct mips_coproc *cop0 = vcpu->arch.cop0; int dc; u32 old_compare = kvm_read_c0_guest_compare(cop0); - ktime_t now; + s32 delta = compare - old_compare; + u32 cause; + ktime_t now = ktime_set(0, 0); /* silence bogus GCC warning */ u32 count; /* if unchanged, must just be an ack */ @@ -633,6 +635,21 @@ void kvm_mips_write_compare(struct kvm_vcpu *vcpu, u32 compare, bool ack) return; } + /* + * If guest CP0_Compare moves forward, CP0_GTOffset should be adjusted + * too to prevent guest CP0_Count hitting guest CP0_Compare. + * + * The new GTOffset corresponds to the new value of CP0_Compare, and is + * set prior to it being written into the guest context. We disable + * preemption until the new value is written to prevent restore of a + * GTOffset corresponding to the old CP0_Compare value. + */ + if (IS_ENABLED(CONFIG_KVM_MIPS_VZ) && delta > 0) { + preempt_disable(); + write_c0_gtoffset(compare - read_c0_count()); + back_to_back_c0_hazard(); + } + /* freeze_hrtimer() takes care of timer interrupts <= count */ dc = kvm_mips_count_disabled(vcpu); if (!dc) @@ -640,12 +657,36 @@ void kvm_mips_write_compare(struct kvm_vcpu *vcpu, u32 compare, bool ack) if (ack) kvm_mips_callbacks->dequeue_timer_int(vcpu); + else if (IS_ENABLED(CONFIG_KVM_MIPS_VZ)) + /* + * With VZ, writing CP0_Compare acks (clears) CP0_Cause.TI, so + * preserve guest CP0_Cause.TI if we don't want to ack it. + */ + cause = kvm_read_c0_guest_cause(cop0); kvm_write_c0_guest_compare(cop0, compare); + if (IS_ENABLED(CONFIG_KVM_MIPS_VZ)) { + if (delta > 0) + preempt_enable(); + + back_to_back_c0_hazard(); + + if (!ack && cause & CAUSEF_TI) + kvm_write_c0_guest_cause(cop0, cause); + } + /* resume_hrtimer() takes care of timer interrupts > count */ if (!dc) kvm_mips_resume_hrtimer(vcpu, now, count); + + /* + * If guest CP0_Compare is moving backward, we delay CP0_GTOffset change + * until after the new CP0_Compare is written, otherwise new guest + * CP0_Count could hit new guest CP0_Compare. + */ + if (IS_ENABLED(CONFIG_KVM_MIPS_VZ) && delta <= 0) + write_c0_gtoffset(compare - read_c0_count()); } /** -- git-series 0.8.10
next prev parent reply other threads:[~2017-03-14 10:26 UTC|newest] Thread overview: 72+ messages / expand[flat|nested] mbox.gz Atom feed top 2017-03-14 10:15 [PATCH v2 0/33] KVM: MIPS: Add VZ support James Hogan 2017-03-14 10:15 ` James Hogan 2017-03-14 10:15 ` [PATCH v2 1/33] MIPS: Add defs & probing of UFR James Hogan 2017-03-14 10:15 ` James Hogan 2017-03-14 10:15 ` [PATCH v2 2/33] MIPS: Separate MAAR V bit into VL and VH for XPA James Hogan 2017-03-14 10:15 ` James Hogan 2017-03-14 10:15 ` [PATCH v2 3/33] MIPS: Probe guest CP0_UserLocal James Hogan 2017-03-14 10:15 ` James Hogan 2017-03-14 10:15 ` [PATCH v2 4/33] MIPS: Probe guest MVH James Hogan 2017-03-14 10:15 ` James Hogan 2017-03-14 10:15 ` [PATCH v2 5/33] MIPS: Add some missing guest CP0 accessors & defs James Hogan 2017-03-14 10:15 ` James Hogan 2017-03-14 10:15 ` [PATCH v2 6/33] MIPS: asm/tlb.h: Add UNIQUE_GUEST_ENTRYHI() macro James Hogan 2017-03-14 10:15 ` James Hogan 2017-03-14 10:15 ` [PATCH v2 7/33] KVM: MIPS: Implement HYPCALL emulation James Hogan 2017-03-14 10:15 ` James Hogan 2017-03-14 10:15 ` [PATCH v2 8/33] KVM: MIPS/Emulate: De-duplicate MMIO emulation James Hogan 2017-03-14 10:15 ` James Hogan 2017-03-14 10:15 ` [PATCH v2 9/33] KVM: MIPS/Emulate: Implement 64-bit " James Hogan 2017-03-14 10:15 ` James Hogan 2017-03-14 10:15 ` [PATCH v2 10/33] KVM: MIPS: Update kvm_lose_fpu() for VZ James Hogan 2017-03-14 10:15 ` James Hogan 2017-03-14 10:15 ` [PATCH v2 11/33] KVM: MIPS: Extend counters & events for VZ GExcCodes James Hogan 2017-03-14 10:15 ` James Hogan 2017-03-14 10:15 ` [PATCH v2 12/33] KVM: MIPS: Add VZ & TE capabilities James Hogan 2017-03-14 10:15 ` James Hogan 2017-03-14 10:15 ` [PATCH v2 13/33] KVM: MIPS: Add 64BIT capability James Hogan 2017-03-14 10:15 ` James Hogan 2017-03-14 10:15 ` [PATCH v2 14/33] KVM: MIPS: Init timer frequency from callback James Hogan 2017-03-14 10:15 ` James Hogan 2017-03-14 10:15 ` [PATCH v2 15/33] KVM: MIPS: Add callback to check extension James Hogan 2017-03-14 10:15 ` James Hogan 2017-03-14 10:15 ` [PATCH v2 16/33] KVM: MIPS: Add hardware_{enable,disable} callback James Hogan 2017-03-14 10:15 ` James Hogan 2017-03-14 10:15 ` [PATCH v2 17/33] KVM: MIPS: Add guest exit exception callback James Hogan 2017-03-14 10:15 ` James Hogan 2017-03-14 10:15 ` [PATCH v2 18/33] KVM: MIPS: Abstract guest CP0 register access for VZ James Hogan 2017-03-14 10:15 ` James Hogan 2017-03-14 10:15 ` [PATCH v2 19/33] KVM: MIPS/Entry: Update entry code to support VZ James Hogan 2017-03-14 10:15 ` James Hogan 2017-03-14 10:15 ` [PATCH v2 20/33] KVM: MIPS/TLB: Add VZ TLB management James Hogan 2017-03-14 10:15 ` James Hogan 2017-03-14 10:15 ` James Hogan [this message] 2017-03-14 10:15 ` [PATCH v2 21/33] KVM: MIPS/Emulate: Update CP0_Compare emulation for VZ James Hogan 2017-03-14 10:15 ` [PATCH v2 22/33] KVM: MIPS/Emulate: Drop CACHE " James Hogan 2017-03-14 10:15 ` James Hogan 2017-03-14 10:15 ` [PATCH v2 23/33] KVM: MIPS: Update exit handler " James Hogan 2017-03-14 10:15 ` James Hogan 2017-03-14 10:15 ` [PATCH v2 24/33] KVM: MIPS: Implement VZ support James Hogan 2017-03-14 10:15 ` James Hogan 2017-03-14 10:15 ` [PATCH v2 25/33] KVM: MIPS: Add VZ support to build system James Hogan 2017-03-14 10:15 ` James Hogan 2017-03-16 11:40 ` kbuild test robot 2017-03-16 11:40 ` kbuild test robot 2017-03-16 12:50 ` James Hogan 2017-03-14 10:15 ` [PATCH v2 26/33] KVM: MIPS/VZ: Support guest CP0_BadInstr[P] James Hogan 2017-03-14 10:15 ` James Hogan 2017-03-14 10:15 ` [PATCH v2 27/33] KVM: MIPS/VZ: Support guest CP0_[X]ContextConfig James Hogan 2017-03-14 10:15 ` James Hogan 2017-03-14 10:15 ` [PATCH v2 28/33] KVM: MIPS/VZ: Support guest segmentation control James Hogan 2017-03-14 10:15 ` James Hogan 2017-03-14 10:15 ` [PATCH v2 29/33] KVM: MIPS/VZ: Support guest hardware page table walker James Hogan 2017-03-14 10:15 ` James Hogan 2017-03-14 10:15 ` [PATCH v2 30/33] KVM: MIPS/VZ: Support guest load-linked bit James Hogan 2017-03-14 10:15 ` James Hogan 2017-03-14 10:15 ` [PATCH v2 31/33] KVM: MIPS/VZ: Emulate MAARs when necessary James Hogan 2017-03-14 10:15 ` James Hogan 2017-03-14 10:15 ` [PATCH v2 32/33] KVM: MIPS/VZ: Support hardware guest timer James Hogan 2017-03-14 10:15 ` James Hogan 2017-03-14 10:15 ` [PATCH v2 33/33] KVM: MIPS/VZ: Trace guest mode changes James Hogan 2017-03-14 10:15 ` James Hogan 2017-03-15 16:32 ` [PATCH v2 0/33] KVM: MIPS: Add VZ support Ralf Baechle
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