[PATCH v5 32/48] KVM: PPC: Book3S HV P9: Read machine check registers while MSR[RI] is 0
From: Nicholas Piggin <npiggin@gmail.com>
Date: 2021-04-01 15:18:38
Subsystem:
kernel virtual machine for powerpc (kvm/powerpc), linux for powerpc (32-bit and 64-bit), the rest · Maintainers:
Madhavan Srinivasan, Michael Ellerman, Linus Torvalds
SRR0/1, DAR, DSISR must all be protected from machine check which can clobber them. Ensure MSR[RI] is clear while they are live. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> --- arch/powerpc/kvm/book3s_hv.c | 11 +++++++-- arch/powerpc/kvm/book3s_hv_interrupt.c | 33 +++++++++++++++++++++++--- arch/powerpc/kvm/book3s_hv_ras.c | 2 ++ 3 files changed, 41 insertions(+), 5 deletions(-)
diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index af0eedcaab8b..5953d1d72f2e 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c@@ -3561,11 +3561,16 @@ static int kvmhv_p9_guest_entry(struct kvm_vcpu *vcpu, u64 time_limit, mtspr(SPRN_BESCR, vcpu->arch.bescr); mtspr(SPRN_WORT, vcpu->arch.wort); mtspr(SPRN_TIDR, vcpu->arch.tid); - mtspr(SPRN_DAR, vcpu->arch.shregs.dar); - mtspr(SPRN_DSISR, vcpu->arch.shregs.dsisr); mtspr(SPRN_AMR, vcpu->arch.amr); mtspr(SPRN_UAMOR, vcpu->arch.uamor); + /* + * DAR, DSISR, and for nested HV, SPRGs must be set with MSR[RI] + * clear (or hstate set appropriately to catch those registers + * being clobbered if we take a MCE or SRESET), so those are done + * later. + */ + if (!(vcpu->arch.ctrl & 1)) mtspr(SPRN_CTRLT, mfspr(SPRN_CTRLF) & ~1);
@@ -3608,6 +3613,8 @@ static int kvmhv_p9_guest_entry(struct kvm_vcpu *vcpu, u64 time_limit, hvregs.vcpu_token = vcpu->vcpu_id; } hvregs.hdec_expiry = time_limit; + mtspr(SPRN_DAR, vcpu->arch.shregs.dar); + mtspr(SPRN_DSISR, vcpu->arch.shregs.dsisr); trap = plpar_hcall_norets(H_ENTER_NESTED, __pa(&hvregs), __pa(&vcpu->arch.regs)); kvmhv_restore_hv_return_state(vcpu, &hvregs);
diff --git a/arch/powerpc/kvm/book3s_hv_interrupt.c b/arch/powerpc/kvm/book3s_hv_interrupt.c
index 15f1b78c5c90..e419b23faa16 100644
--- a/arch/powerpc/kvm/book3s_hv_interrupt.c
+++ b/arch/powerpc/kvm/book3s_hv_interrupt.c@@ -132,6 +132,7 @@ int kvmhv_vcpu_entry_p9(struct kvm_vcpu *vcpu, u64 time_limit, unsigned long lpc s64 hdec; u64 tb, purr, spurr; u64 *exsave; + bool ri_set; unsigned long msr = mfmsr(); int trap; unsigned long host_hfscr = mfspr(SPRN_HFSCR);
@@ -203,9 +204,6 @@ int kvmhv_vcpu_entry_p9(struct kvm_vcpu *vcpu, u64 time_limit, unsigned long lpc */ mtspr(SPRN_HDEC, hdec); - mtspr(SPRN_SRR0, vcpu->arch.shregs.srr0); - mtspr(SPRN_SRR1, vcpu->arch.shregs.srr1); - start_timing(vcpu, &vcpu->arch.rm_entry); vcpu->arch.ceded = 0;
@@ -231,6 +229,13 @@ int kvmhv_vcpu_entry_p9(struct kvm_vcpu *vcpu, u64 time_limit, unsigned long lpc */ mtspr(SPRN_HDSISR, HDSISR_CANARY); + __mtmsrd(0, 1); /* clear RI */ + + mtspr(SPRN_DAR, vcpu->arch.shregs.dar); + mtspr(SPRN_DSISR, vcpu->arch.shregs.dsisr); + mtspr(SPRN_SRR0, vcpu->arch.shregs.srr0); + mtspr(SPRN_SRR1, vcpu->arch.shregs.srr1); + accumulate_time(vcpu, &vcpu->arch.guest_time); local_paca->kvm_hstate.in_guest = KVM_GUEST_MODE_GUEST_HV_FAST;
@@ -248,7 +253,13 @@ int kvmhv_vcpu_entry_p9(struct kvm_vcpu *vcpu, u64 time_limit, unsigned long lpc /* 0x2 bit for HSRR is only used by PR and P7/8 HV paths, clear it */ trap = local_paca->kvm_hstate.scratch0 & ~0x2; + + /* HSRR interrupts leave MSR[RI] unchanged, SRR interrupts clear it. */ + ri_set = false; if (likely(trap > BOOK3S_INTERRUPT_MACHINE_CHECK)) { + if (trap != BOOK3S_INTERRUPT_SYSCALL && + (vcpu->arch.shregs.msr & MSR_RI)) + ri_set = true; exsave = local_paca->exgen; } else if (trap == BOOK3S_INTERRUPT_SYSTEM_RESET) { exsave = local_paca->exnmi;
@@ -258,6 +269,22 @@ int kvmhv_vcpu_entry_p9(struct kvm_vcpu *vcpu, u64 time_limit, unsigned long lpc vcpu->arch.regs.gpr[1] = local_paca->kvm_hstate.scratch1; vcpu->arch.regs.gpr[3] = local_paca->kvm_hstate.scratch2; + + /* + * Only set RI after reading machine check regs (DAR, DSISR, SRR0/1) + * and hstate scratch (which we need to move into exsave to make + * re-entrant vs SRESET/MCE) + */ + if (ri_set) { + if (unlikely(!(mfmsr() & MSR_RI))) { + __mtmsrd(MSR_RI, 1); + WARN_ON_ONCE(1); + } + } else { + WARN_ON_ONCE(mfmsr() & MSR_RI); + __mtmsrd(MSR_RI, 1); + } + vcpu->arch.regs.gpr[9] = exsave[EX_R9/sizeof(u64)]; vcpu->arch.regs.gpr[10] = exsave[EX_R10/sizeof(u64)]; vcpu->arch.regs.gpr[11] = exsave[EX_R11/sizeof(u64)];
diff --git a/arch/powerpc/kvm/book3s_hv_ras.c b/arch/powerpc/kvm/book3s_hv_ras.c
index d4bca93b79f6..8d8a4d5f0b55 100644
--- a/arch/powerpc/kvm/book3s_hv_ras.c
+++ b/arch/powerpc/kvm/book3s_hv_ras.c@@ -199,6 +199,8 @@ static void kvmppc_tb_resync_done(void) * know about the exact state of the TB value. Resync TB call will * restore TB to host timebase. * + * This could use the new OPAL_HANDLE_HMI2 to avoid resyncing TB every time. + * * Things to consider: * - On TB error, HMI interrupt is reported on all the threads of the core * that has encountered TB error irrespective of split-core mode.
--
2.23.0