From 6c85b7bc637b64e681760f62c0eafba2f56745c6 Mon Sep 17 00:00:00 2001 From: Sukadev Bhattiprolu Date: Thu, 22 Aug 2019 00:48:38 -0300 Subject: [PATCH] powerpc/kvm: Use UV_RETURN ucall to return to ultravisor When an SVM makes an hypercall or incurs some other exception, the Ultravisor usually forwards (a.k.a. reflects) the exceptions to the Hypervisor. After processing the exception, Hypervisor uses the UV_RETURN ultracall to return control back to the SVM. The expected register state on entry to this ultracall is: * Non-volatile registers are restored to their original values. * If returning from an hypercall, register R0 contains the return value (unlike other ultracalls) and, registers R4 through R12 contain any output values of the hypercall. * R3 contains the ultracall number, i.e UV_RETURN. * If returning with a synthesized interrupt, R2 contains the synthesized interrupt number. Thanks to input from Paul Mackerras, Ram Pai and Mike Anderson. Signed-off-by: Sukadev Bhattiprolu Signed-off-by: Claudio Carvalho Acked-by: Paul Mackerras Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20190822034838.27876-8-cclaudio@linux.ibm.com --- arch/powerpc/include/asm/kvm_host.h | 1 + arch/powerpc/include/asm/ultravisor-api.h | 1 + arch/powerpc/kernel/asm-offsets.c | 1 + arch/powerpc/kvm/book3s_hv_rmhandlers.S | 39 ++++++++++++++++++++++++++----- 4 files changed, 36 insertions(+), 6 deletions(-) diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h index e6e5f59..4bb552d 100644 --- a/arch/powerpc/include/asm/kvm_host.h +++ b/arch/powerpc/include/asm/kvm_host.h @@ -283,6 +283,7 @@ struct kvm_arch { cpumask_t cpu_in_guest; u8 radix; u8 fwnmi_enabled; + u8 secure_guest; bool threads_indep; bool nested_enable; pgd_t *pgtable; diff --git a/arch/powerpc/include/asm/ultravisor-api.h b/arch/powerpc/include/asm/ultravisor-api.h index 8cd49ab..6a0f9c74 100644 --- a/arch/powerpc/include/asm/ultravisor-api.h +++ b/arch/powerpc/include/asm/ultravisor-api.h @@ -24,5 +24,6 @@ /* opcodes */ #define UV_WRITE_PATE 0xF104 +#define UV_RETURN 0xF11C #endif /* _ASM_POWERPC_ULTRAVISOR_API_H */ diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c index 4ccb6b3..484f54d 100644 --- a/arch/powerpc/kernel/asm-offsets.c +++ b/arch/powerpc/kernel/asm-offsets.c @@ -506,6 +506,7 @@ int main(void) OFFSET(KVM_VRMA_SLB_V, kvm, arch.vrma_slb_v); OFFSET(KVM_RADIX, kvm, arch.radix); OFFSET(KVM_FWNMI, kvm, arch.fwnmi_enabled); + OFFSET(KVM_SECURE_GUEST, kvm, arch.secure_guest); OFFSET(VCPU_DSISR, kvm_vcpu, arch.shregs.dsisr); OFFSET(VCPU_DAR, kvm_vcpu, arch.shregs.dar); OFFSET(VCPU_VPA, kvm_vcpu, arch.vpa.pinned_addr); diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S index 07181d0..9a05b0d 100644 --- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S +++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S @@ -29,6 +29,7 @@ #include #include #include +#include /* Sign-extend HDEC if not on POWER9 */ #define EXTEND_HDEC(reg) \ @@ -1085,16 +1086,10 @@ BEGIN_FTR_SECTION END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR) ld r5, VCPU_LR(r4) - ld r6, VCPU_CR(r4) mtlr r5 - mtcr r6 ld r1, VCPU_GPR(R1)(r4) - ld r2, VCPU_GPR(R2)(r4) - ld r3, VCPU_GPR(R3)(r4) ld r5, VCPU_GPR(R5)(r4) - ld r6, VCPU_GPR(R6)(r4) - ld r7, VCPU_GPR(R7)(r4) ld r8, VCPU_GPR(R8)(r4) ld r9, VCPU_GPR(R9)(r4) ld r10, VCPU_GPR(R10)(r4) @@ -1112,10 +1107,42 @@ BEGIN_FTR_SECTION mtspr SPRN_HDSISR, r0 END_FTR_SECTION_IFSET(CPU_FTR_ARCH_300) + ld r6, VCPU_KVM(r4) + lbz r7, KVM_SECURE_GUEST(r6) + cmpdi r7, 0 + ld r6, VCPU_GPR(R6)(r4) + ld r7, VCPU_GPR(R7)(r4) + bne ret_to_ultra + + lwz r0, VCPU_CR(r4) + mtcr r0 + ld r0, VCPU_GPR(R0)(r4) + ld r2, VCPU_GPR(R2)(r4) + ld r3, VCPU_GPR(R3)(r4) ld r4, VCPU_GPR(R4)(r4) HRFI_TO_GUEST b . +/* + * Use UV_RETURN ultracall to return control back to the Ultravisor after + * processing an hypercall or interrupt that was forwarded (a.k.a. reflected) + * to the Hypervisor. + * + * All registers have already been loaded, except: + * R0 = hcall result + * R2 = SRR1, so UV can detect a synthesized interrupt (if any) + * R3 = UV_RETURN + */ +ret_to_ultra: + lwz r0, VCPU_CR(r4) + mtcr r0 + + ld r0, VCPU_GPR(R3)(r4) + mfspr r2, SPRN_SRR1 + li r3, 0 + ori r3, r3, UV_RETURN + ld r4, VCPU_GPR(R4)(r4) + sc 2 /* * Enter the guest on a P9 or later system where we have exactly -- 2.7.4