From: James Hogan <james.hogan@imgtec.com> To: <linux-mips@linux-mips.org> Cc: "James Hogan" <james.hogan@imgtec.com>, "Paolo Bonzini" <pbonzini@redhat.com>, "Radim Krčmář" <rkrcmar@redhat.com>, "Ralf Baechle" <ralf@linux-mips.org>, kvm@vger.kernel.org Subject: [PATCH 11/30] KVM: MIPS/T&E: Restore host asid on return to host Date: Fri, 6 Jan 2017 01:32:43 +0000 [thread overview] Message-ID: <48d15f0c804c868e5bc413fcd7052c290d8db5db.1483665879.git-series.james.hogan@imgtec.com> (raw) In-Reply-To: <cover.d6d201de414322ed2c1372e164254e6055ef7db9.1483665879.git-series.james.hogan@imgtec.com> We only need the guest ASID loaded while in guest context, i.e. while running guest code and while handling guest exits. We load the guest ASID when entering the guest, however we restore the host ASID later than necessary, when the VCPU state is saved i.e. vcpu_put() or slightly earlier if preempted after returning to the host. This mismatch is both unpleasant and causes redundant host ASID restores in kvm_trap_emul_vcpu_put(). Lets explicitly restore the host ASID when returning to the host, and don't bother restoring the host ASID on context switch in unless we're already in guest context. 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/trap_emul.c | 27 ++++++++++++++++++++------- 1 file changed, 20 insertions(+), 7 deletions(-) diff --git a/arch/mips/kvm/trap_emul.c b/arch/mips/kvm/trap_emul.c index 92734d095c94..3e1dbcbcea85 100644 --- a/arch/mips/kvm/trap_emul.c +++ b/arch/mips/kvm/trap_emul.c @@ -680,14 +680,17 @@ static int kvm_trap_emul_vcpu_put(struct kvm_vcpu *vcpu, int cpu) { kvm_lose_fpu(vcpu); - if (((cpu_context(cpu, current->mm) ^ asid_cache(cpu)) & - asid_version_mask(cpu))) { - kvm_debug("%s: Dropping MMU Context: %#lx\n", __func__, - cpu_context(cpu, current->mm)); - drop_mmu_context(current->mm, cpu); + if (current->flags & PF_VCPU) { + /* Restore normal Linux process memory map */ + if (((cpu_context(cpu, current->mm) ^ asid_cache(cpu)) & + asid_version_mask(cpu))) { + kvm_debug("%s: Dropping MMU Context: %#lx\n", __func__, + cpu_context(cpu, current->mm)); + get_new_mmu_context(current->mm, cpu); + } + write_c0_entryhi(cpu_asid(cpu, current->mm)); + ehb(); } - write_c0_entryhi(cpu_asid(cpu, current->mm)); - ehb(); return 0; } @@ -720,6 +723,7 @@ static void kvm_trap_emul_vcpu_reenter(struct kvm_run *run, static int kvm_trap_emul_vcpu_run(struct kvm_run *run, struct kvm_vcpu *vcpu) { + int cpu; int r; /* Check if we have any exceptions/interrupts pending */ @@ -733,6 +737,15 @@ static int kvm_trap_emul_vcpu_run(struct kvm_run *run, struct kvm_vcpu *vcpu) r = vcpu->arch.vcpu_run(run, vcpu); + /* We may have migrated while handling guest exits */ + cpu = smp_processor_id(); + + /* Restore normal Linux process memory map */ + if (((cpu_context(cpu, current->mm) ^ asid_cache(cpu)) & + asid_version_mask(cpu))) + get_new_mmu_context(current->mm, cpu); + write_c0_entryhi(cpu_asid(cpu, current->mm)); + htw_start(); return r; -- 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 Cc: "James Hogan" <james.hogan@imgtec.com>, "Paolo Bonzini" <pbonzini@redhat.com>, "Radim Krčmář" <rkrcmar@redhat.com>, "Ralf Baechle" <ralf@linux-mips.org>, kvm@vger.kernel.org Subject: [PATCH 11/30] KVM: MIPS/T&E: Restore host asid on return to host Date: Fri, 6 Jan 2017 01:32:43 +0000 [thread overview] Message-ID: <48d15f0c804c868e5bc413fcd7052c290d8db5db.1483665879.git-series.james.hogan@imgtec.com> (raw) Message-ID: <20170106013243.dJt4o-HNUjKHANvqCD_WESub3pClG8K9S2trfqVkTtA@z> (raw) In-Reply-To: <cover.d6d201de414322ed2c1372e164254e6055ef7db9.1483665879.git-series.james.hogan@imgtec.com> We only need the guest ASID loaded while in guest context, i.e. while running guest code and while handling guest exits. We load the guest ASID when entering the guest, however we restore the host ASID later than necessary, when the VCPU state is saved i.e. vcpu_put() or slightly earlier if preempted after returning to the host. This mismatch is both unpleasant and causes redundant host ASID restores in kvm_trap_emul_vcpu_put(). Lets explicitly restore the host ASID when returning to the host, and don't bother restoring the host ASID on context switch in unless we're already in guest context. 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/trap_emul.c | 27 ++++++++++++++++++++------- 1 file changed, 20 insertions(+), 7 deletions(-) diff --git a/arch/mips/kvm/trap_emul.c b/arch/mips/kvm/trap_emul.c index 92734d095c94..3e1dbcbcea85 100644 --- a/arch/mips/kvm/trap_emul.c +++ b/arch/mips/kvm/trap_emul.c @@ -680,14 +680,17 @@ static int kvm_trap_emul_vcpu_put(struct kvm_vcpu *vcpu, int cpu) { kvm_lose_fpu(vcpu); - if (((cpu_context(cpu, current->mm) ^ asid_cache(cpu)) & - asid_version_mask(cpu))) { - kvm_debug("%s: Dropping MMU Context: %#lx\n", __func__, - cpu_context(cpu, current->mm)); - drop_mmu_context(current->mm, cpu); + if (current->flags & PF_VCPU) { + /* Restore normal Linux process memory map */ + if (((cpu_context(cpu, current->mm) ^ asid_cache(cpu)) & + asid_version_mask(cpu))) { + kvm_debug("%s: Dropping MMU Context: %#lx\n", __func__, + cpu_context(cpu, current->mm)); + get_new_mmu_context(current->mm, cpu); + } + write_c0_entryhi(cpu_asid(cpu, current->mm)); + ehb(); } - write_c0_entryhi(cpu_asid(cpu, current->mm)); - ehb(); return 0; } @@ -720,6 +723,7 @@ static void kvm_trap_emul_vcpu_reenter(struct kvm_run *run, static int kvm_trap_emul_vcpu_run(struct kvm_run *run, struct kvm_vcpu *vcpu) { + int cpu; int r; /* Check if we have any exceptions/interrupts pending */ @@ -733,6 +737,15 @@ static int kvm_trap_emul_vcpu_run(struct kvm_run *run, struct kvm_vcpu *vcpu) r = vcpu->arch.vcpu_run(run, vcpu); + /* We may have migrated while handling guest exits */ + cpu = smp_processor_id(); + + /* Restore normal Linux process memory map */ + if (((cpu_context(cpu, current->mm) ^ asid_cache(cpu)) & + asid_version_mask(cpu))) + get_new_mmu_context(current->mm, cpu); + write_c0_entryhi(cpu_asid(cpu, current->mm)); + htw_start(); return r; -- git-series 0.8.10
next prev parent reply other threads:[~2017-01-06 1:38 UTC|newest] Thread overview: 67+ messages / expand[flat|nested] mbox.gz Atom feed top 2017-01-06 1:32 [PATCH 0/30] KVM: MIPS: Implement GVA page tables James Hogan 2017-01-06 1:32 ` James Hogan 2017-01-06 1:32 ` [PATCH 1/30] mm: Export init_mm for MIPS KVM use of pgd_alloc() James Hogan 2017-01-06 1:32 ` James Hogan 2017-01-17 16:23 ` Ralf Baechle 2017-01-17 16:27 ` Ralf Baechle 2017-01-06 1:32 ` [PATCH 2/30] MIPS: Export pgd/pmd symbols for KVM James Hogan 2017-01-06 1:32 ` James Hogan 2017-01-17 16:24 ` Ralf Baechle 2017-01-06 1:32 ` [PATCH 3/30] MIPS: uasm: Add include guards in asm/uasm.h James Hogan 2017-01-06 1:32 ` James Hogan 2017-01-17 16:25 ` Ralf Baechle 2017-01-06 1:32 ` [PATCH 4/30] MIPS: Export some tlbex internals for KVM to use James Hogan 2017-01-06 1:32 ` James Hogan 2017-01-17 16:26 ` Ralf Baechle 2017-01-06 1:32 ` [PATCH 5/30] KVM: MIPS: Drop partial KVM_NMI implementation James Hogan 2017-01-06 1:32 ` James Hogan 2017-01-06 1:32 ` [PATCH 6/30] KVM: MIPS/MMU: Simplify ASID restoration James Hogan 2017-01-06 1:32 ` James Hogan 2017-01-06 1:32 ` [PATCH 7/30] KVM: MIPS: Convert get/set_regs -> vcpu_load/put James Hogan 2017-01-06 1:32 ` James Hogan 2017-01-06 1:32 ` [PATCH 8/30] KVM: MIPS/MMU: Move preempt/ASID handling to implementation James Hogan 2017-01-06 1:32 ` James Hogan 2017-01-06 1:32 ` [PATCH 9/30] KVM: MIPS: Remove duplicated ASIDs from vcpu James Hogan 2017-01-06 1:32 ` James Hogan 2017-01-06 1:32 ` [PATCH 10/30] KVM: MIPS: Add vcpu_run() & vcpu_reenter() callbacks James Hogan 2017-01-06 1:32 ` James Hogan 2017-01-06 1:32 ` James Hogan [this message] 2017-01-06 1:32 ` [PATCH 11/30] KVM: MIPS/T&E: Restore host asid on return to host James Hogan 2017-01-06 1:32 ` [PATCH 12/30] KVM: MIPS/T&E: active_mm = init_mm in guest context James Hogan 2017-01-06 1:32 ` James Hogan 2017-01-06 1:32 ` [PATCH 13/30] KVM: MIPS: Wire up vcpu uninit James Hogan 2017-01-06 1:32 ` James Hogan 2017-01-06 1:32 ` [PATCH 14/30] KVM: MIPS/T&E: Allocate GVA -> HPA page tables James Hogan 2017-01-06 1:32 ` James Hogan 2017-01-06 1:32 ` [PATCH 15/30] KVM: MIPS/T&E: Activate GVA page tables in guest context James Hogan 2017-01-06 1:32 ` James Hogan 2017-01-06 1:32 ` [PATCH 16/30] KVM: MIPS: Support NetLogic KScratch registers James Hogan 2017-01-06 1:32 ` James Hogan 2017-01-06 1:32 ` [PATCH 17/30] KVM: MIPS: Add fast path TLB refill handler James Hogan 2017-01-06 1:32 ` James Hogan 2017-01-06 1:32 ` [PATCH 18/30] KVM: MIPS/TLB: Fix off-by-one in TLB invalidate James Hogan 2017-01-06 1:32 ` James Hogan 2017-01-06 1:32 ` [PATCH 19/30] KVM: MIPS/TLB: Generalise host TLB invalidate to kernel ASID James Hogan 2017-01-06 1:32 ` James Hogan 2017-01-06 1:32 ` [PATCH 20/30] KVM: MIPS/MMU: Invalidate GVA PTs on ASID changes James Hogan 2017-01-06 1:32 ` James Hogan 2017-01-06 1:32 ` [PATCH 21/30] KVM: MIPS/MMU: Invalidate stale GVA PTEs on TLBW James Hogan 2017-01-06 1:32 ` James Hogan 2017-01-06 1:32 ` [PATCH 22/30] KVM: MIPS/MMU: Convert KSeg0 faults to page tables James Hogan 2017-01-06 1:32 ` James Hogan 2017-01-06 1:32 ` [PATCH 23/30] KVM: MIPS/MMU: Convert TLB mapped " James Hogan 2017-01-06 1:32 ` James Hogan 2017-01-06 1:32 ` [PATCH 24/30] KVM: MIPS/MMU: Convert commpage fault handling " James Hogan 2017-01-06 1:32 ` James Hogan 2017-01-06 1:32 ` [PATCH 25/30] KVM: MIPS: Drop vm_init() callback James Hogan 2017-01-06 1:32 ` James Hogan 2017-01-06 1:32 ` [PATCH 26/30] KVM: MIPS: Use uaccess to read/modify guest instructions James Hogan 2017-01-06 1:32 ` James Hogan 2017-01-06 1:32 ` [PATCH 27/30] KVM: MIPS/Emulate: Fix CACHE emulation for EVA hosts James Hogan 2017-01-06 1:32 ` James Hogan 2017-01-06 1:33 ` [PATCH 28/30] KVM: MIPS/TLB: Drop kvm_local_flush_tlb_all() James Hogan 2017-01-06 1:33 ` James Hogan 2017-01-06 1:33 ` [PATCH 29/30] KVM: MIPS/Emulate: Drop redundant TLB flushes on exceptions James Hogan 2017-01-06 1:33 ` James Hogan 2017-01-06 1:33 ` [PATCH 30/30] KVM: MIPS/MMU: Drop kvm_get_new_mmu_context() James Hogan 2017-01-06 1:33 ` James Hogan
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