KVM: PPC: Call SLB patching code in interrupt safe manner
Currently we're racy when doing the transition from IR=1 to IR=0, from the module memory entry code to the real mode SLB switching code. To work around that I took a look at the RTAS entry code which is faced with a similar problem and did the same thing: A small helper in linear mapped memory that does mtmsr with IR=0 and then RFIs info the actual handler. Thanks to that trick we can safely take page faults in the entry code and only need to be really wary of what to do as of the SLB switching part. Signed-off-by: Alexander Graf <agraf@suse.de> Signed-off-by: Avi Kivity <avi@redhat.com>
This commit is contained in:
Alexander Graf
Marcelo Tosatti
parent
bc90923e27
commit
021ec9c69f
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@ -121,6 +121,7 @@ extern void kvmppc_set_bat(struct kvm_vcpu *vcpu, struct kvmppc_bat *bat,
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extern u32 kvmppc_trampoline_lowmem;
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extern u32 kvmppc_trampoline_enter;
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extern void kvmppc_rmcall(ulong srr0, ulong srr1);
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static inline struct kvmppc_vcpu_book3s *to_book3s(struct kvm_vcpu *vcpu)
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{
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@ -69,7 +69,6 @@ struct kvmppc_book3s_shadow_vcpu {
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ulong scratch0;
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ulong scratch1;
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ulong vmhandler;
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ulong rmhandler;
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};
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#endif /*__ASSEMBLY__ */
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@ -167,6 +167,7 @@ struct kvm_vcpu_arch {
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ulong trampoline_lowmem;
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ulong trampoline_enter;
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ulong highmem_handler;
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ulong rmcall;
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ulong host_paca_phys;
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struct kvmppc_mmu mmu;
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#endif
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@ -214,8 +214,6 @@ int main(void)
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DEFINE(PACA_KVM_HOST_R2, offsetof(struct paca_struct, shadow_vcpu.host_r2));
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DEFINE(PACA_KVM_VMHANDLER, offsetof(struct paca_struct,
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shadow_vcpu.vmhandler));
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DEFINE(PACA_KVM_RMHANDLER, offsetof(struct paca_struct,
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shadow_vcpu.rmhandler));
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DEFINE(PACA_KVM_SCRATCH0, offsetof(struct paca_struct,
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shadow_vcpu.scratch0));
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DEFINE(PACA_KVM_SCRATCH1, offsetof(struct paca_struct,
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@ -438,6 +436,7 @@ int main(void)
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DEFINE(VCPU_TRAMPOLINE_LOWMEM, offsetof(struct kvm_vcpu, arch.trampoline_lowmem));
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DEFINE(VCPU_TRAMPOLINE_ENTER, offsetof(struct kvm_vcpu, arch.trampoline_enter));
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DEFINE(VCPU_HIGHMEM_HANDLER, offsetof(struct kvm_vcpu, arch.highmem_handler));
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DEFINE(VCPU_RMCALL, offsetof(struct kvm_vcpu, arch.rmcall));
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DEFINE(VCPU_HFLAGS, offsetof(struct kvm_vcpu, arch.hflags));
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#else
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DEFINE(VCPU_CR, offsetof(struct kvm_vcpu, arch.cr));
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@ -919,6 +919,7 @@ struct kvm_vcpu *kvmppc_core_vcpu_create(struct kvm *kvm, unsigned int id)
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vcpu->arch.trampoline_lowmem = kvmppc_trampoline_lowmem;
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vcpu->arch.trampoline_enter = kvmppc_trampoline_enter;
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vcpu->arch.highmem_handler = (ulong)kvmppc_handler_highmem;
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vcpu->arch.rmcall = *(ulong*)kvmppc_rmcall;
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vcpu->arch.shadow_msr = MSR_USER64;
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@ -22,3 +22,4 @@
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EXPORT_SYMBOL_GPL(kvmppc_trampoline_enter);
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EXPORT_SYMBOL_GPL(kvmppc_trampoline_lowmem);
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EXPORT_SYMBOL_GPL(kvmppc_rmcall);
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@ -95,17 +95,14 @@ kvm_start_entry:
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ld r3, VCPU_HIGHMEM_HANDLER(r4)
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std r3, PACA_KVM_VMHANDLER(r13)
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ld r3, VCPU_TRAMPOLINE_ENTER(r4)
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std r3, PACA_KVM_RMHANDLER(r13)
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kvm_start_lightweight:
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ld r9, VCPU_PC(r4) /* r9 = vcpu->arch.pc */
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ld r10, VCPU_SHADOW_MSR(r4) /* r10 = vcpu->arch.shadow_msr */
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/* Load some guest state in the respective registers */
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ld r3, VCPU_CTR(r4) /* r3 = vcpu->arch.ctr */
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mtctr r3 /* CTR = r3 */
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ld r5, VCPU_CTR(r4) /* r5 = vcpu->arch.ctr */
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/* will be swapped in by rmcall */
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ld r3, VCPU_LR(r4) /* r3 = vcpu->arch.lr */
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mtlr r3 /* LR = r3 */
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@ -131,22 +128,14 @@ kvm_start_lightweight:
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no_dcbz32_on:
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/* This sets the Magic value for the trampoline */
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ld r6, VCPU_RMCALL(r4)
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mtctr r6
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/* XXX this needs to move into a safe function, so we can
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be sure we don't get any interrupts */
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li r11, 1
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stb r11, PACA_KVM_IN_GUEST(r13)
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ld r3, PACA_KVM_RMHANDLER(r13)
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mtsrr0 r3
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LOAD_REG_IMMEDIATE(r3, MSR_KERNEL & ~(MSR_IR | MSR_DR))
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mtsrr1 r3
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ld r3, VCPU_TRAMPOLINE_ENTER(r4)
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LOAD_REG_IMMEDIATE(r4, MSR_KERNEL & ~(MSR_IR | MSR_DR))
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/* Jump to SLB patching handlder and into our guest */
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RFI
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bctr
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/*
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* This is the handler in module memory. It gets jumped at from the
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@ -140,6 +140,24 @@ kvmppc_handler_lowmem_trampoline:
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blr
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kvmppc_handler_lowmem_trampoline_end:
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/*
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* Call a function in real mode
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*
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* Input Registers:
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*
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* R3 = function
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* R4 = MSR
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* R5 = CTR
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*
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*/
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_GLOBAL(kvmppc_rmcall)
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mtmsr r4 /* Disable relocation, so mtsrr
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doesn't get interrupted */
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mtctr r5
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mtsrr0 r3
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mtsrr1 r4
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RFI
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.global kvmppc_trampoline_lowmem
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kvmppc_trampoline_lowmem:
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.long kvmppc_handler_lowmem_trampoline - _stext
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@ -63,6 +63,10 @@ kvmppc_handler_trampoline_enter:
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mtsrr0 r9
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mtsrr1 r10
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/* Activate guest mode, so faults get handled by KVM */
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li r11, KVM_GUEST_MODE_GUEST
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stb r11, PACA_KVM_IN_GUEST(r13)
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/* Remove LPAR shadow entries */
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#if SLB_NUM_BOLTED == 3
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