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Message-ID: <20241109063301.105289-2-gautam@linux.ibm.com>
Date: Sat, 9 Nov 2024 12:02:55 +0530
From: Gautam Menghani <gautam@...ux.ibm.com>
To: mpe@...erman.id.au, npiggin@...il.com, christophe.leroy@...roup.eu,
naveen@...nel.org, maddy@...ux.ibm.com, vaibhav@...ux.ibm.com
Cc: Gautam Menghani <gautam@...ux.ibm.com>, linuxppc-dev@...ts.ozlabs.org,
kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 1/3] Revert "KVM: PPC: Book3S HV Nested: Stop forwarding all HFUs to L1"
This reverts commit 7c3ded5735141ff4d049747c9f76672a8b737c49.
On PowerNV, when a nested guest tries to use a feature prohibited by
HFSCR, the nested hypervisor (L1) should get a H_FAC_UNAVAILABLE trap
so that L1 can emulate the feature. But with the change introduced by
commit 7c3ded573514 ("KVM: PPC: Book3S HV Nested: Stop forwarding all HFUs
to L1") the L1 ends up getting a H_EMUL_ASSIST because of which, the L1
ends up injecting a SIGILL when L2 (nested guest) tries to use doorbells.
Reviewed-by: Nicholas Piggin <npiggin@...il.com>
Signed-off-by: Gautam Menghani <gautam@...ux.ibm.com>
---
arch/powerpc/kvm/book3s_hv.c | 31 ++-----------------------------
1 file changed, 2 insertions(+), 29 deletions(-)
diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index ad8dc4ccdaab..0a8f143e0a75 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -2060,36 +2060,9 @@ static int kvmppc_handle_nested_exit(struct kvm_vcpu *vcpu)
fallthrough; /* go to facility unavailable handler */
#endif
- case BOOK3S_INTERRUPT_H_FAC_UNAVAIL: {
- u64 cause = vcpu->arch.hfscr >> 56;
-
- /*
- * Only pass HFU interrupts to the L1 if the facility is
- * permitted but disabled by the L1's HFSCR, otherwise
- * the interrupt does not make sense to the L1 so turn
- * it into a HEAI.
- */
- if (!(vcpu->arch.hfscr_permitted & (1UL << cause)) ||
- (vcpu->arch.nested_hfscr & (1UL << cause))) {
- ppc_inst_t pinst;
- vcpu->arch.trap = BOOK3S_INTERRUPT_H_EMUL_ASSIST;
-
- /*
- * If the fetch failed, return to guest and
- * try executing it again.
- */
- r = kvmppc_get_last_inst(vcpu, INST_GENERIC, &pinst);
- vcpu->arch.emul_inst = ppc_inst_val(pinst);
- if (r != EMULATE_DONE)
- r = RESUME_GUEST;
- else
- r = RESUME_HOST;
- } else {
- r = RESUME_HOST;
- }
-
+ case BOOK3S_INTERRUPT_H_FAC_UNAVAIL:
+ r = RESUME_HOST;
break;
- }
case BOOK3S_INTERRUPT_HV_RM_HARD:
vcpu->arch.trap = 0;
--
2.45.2
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