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From: Nicholas Piggin <npiggin@gmail.com>
To: kvm-ppc@vger.kernel.org
Cc: Alexey Kardashevskiy <aik@ozlabs.ru>,
	linuxppc-dev@lists.ozlabs.org,
	Nicholas Piggin <npiggin@gmail.com>
Subject: [PATCH 1/2] KVM: PPC: Book3S: Fix CONFIG_TRANSACTIONAL_MEM=n crash
Date: Fri, 16 Jul 2021 12:43:09 +1000	[thread overview]
Message-ID: <20210716024310.164448-1-npiggin@gmail.com> (raw)

When running CPU_FTR_P9_TM_HV_ASSIST, HFSCR[TM] is set for the guest
even if the host has CONFIG_TRANSACTIONAL_MEM=n, which causes it to be
unprepared to handle guest exits while transactional.

Normal guests don't have a problem because the HTM capability will not
be advertised, but a rogue or buggy one could crash the host.

Reported-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Fixes: 4bb3c7a0208f ("KVM: PPC: Book3S HV: Work around transactional memory bugs in POWER9")
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
 arch/powerpc/kvm/book3s_hv.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 1d1fcc290fca..085fb8ecbf68 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -2697,8 +2697,10 @@ static int kvmppc_core_vcpu_create_hv(struct kvm_vcpu *vcpu)
 		HFSCR_DSCR | HFSCR_VECVSX | HFSCR_FP | HFSCR_PREFIX;
 	if (cpu_has_feature(CPU_FTR_HVMODE)) {
 		vcpu->arch.hfscr &= mfspr(SPRN_HFSCR);
+#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
 		if (cpu_has_feature(CPU_FTR_P9_TM_HV_ASSIST))
 			vcpu->arch.hfscr |= HFSCR_TM;
+#endif
 	}
 	if (cpu_has_feature(CPU_FTR_TM_COMP))
 		vcpu->arch.hfscr |= HFSCR_TM;
-- 
2.23.0


WARNING: multiple messages have this Message-ID (diff)
From: Nicholas Piggin <npiggin@gmail.com>
To: kvm-ppc@vger.kernel.org
Cc: Alexey Kardashevskiy <aik@ozlabs.ru>,
	linuxppc-dev@lists.ozlabs.org,
	Nicholas Piggin <npiggin@gmail.com>
Subject: [PATCH 1/2] KVM: PPC: Book3S: Fix CONFIG_TRANSACTIONAL_MEM=n crash
Date: Fri, 16 Jul 2021 02:43:09 +0000	[thread overview]
Message-ID: <20210716024310.164448-1-npiggin@gmail.com> (raw)

When running CPU_FTR_P9_TM_HV_ASSIST, HFSCR[TM] is set for the guest
even if the host has CONFIG_TRANSACTIONAL_MEM=n, which causes it to be
unprepared to handle guest exits while transactional.

Normal guests don't have a problem because the HTM capability will not
be advertised, but a rogue or buggy one could crash the host.

Reported-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Fixes: 4bb3c7a0208f ("KVM: PPC: Book3S HV: Work around transactional memory bugs in POWER9")
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
 arch/powerpc/kvm/book3s_hv.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 1d1fcc290fca..085fb8ecbf68 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -2697,8 +2697,10 @@ static int kvmppc_core_vcpu_create_hv(struct kvm_vcpu *vcpu)
 		HFSCR_DSCR | HFSCR_VECVSX | HFSCR_FP | HFSCR_PREFIX;
 	if (cpu_has_feature(CPU_FTR_HVMODE)) {
 		vcpu->arch.hfscr &= mfspr(SPRN_HFSCR);
+#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
 		if (cpu_has_feature(CPU_FTR_P9_TM_HV_ASSIST))
 			vcpu->arch.hfscr |= HFSCR_TM;
+#endif
 	}
 	if (cpu_has_feature(CPU_FTR_TM_COMP))
 		vcpu->arch.hfscr |= HFSCR_TM;
-- 
2.23.0

             reply	other threads:[~2021-07-16  2:43 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-16  2:43 Nicholas Piggin [this message]
2021-07-16  2:43 ` [PATCH 1/2] KVM: PPC: Book3S: Fix CONFIG_TRANSACTIONAL_MEM=n crash Nicholas Piggin
2021-07-16  2:43 ` [PATCH 2/2] KVM: PPC: Fix kvm_arch_vcpu_ioctl vcpu_load leak Nicholas Piggin
2021-07-16  2:43   ` Nicholas Piggin
2021-07-21  7:38 ` [PATCH 1/2] KVM: PPC: Book3S: Fix CONFIG_TRANSACTIONAL_MEM=n crash Michael Ellerman
2021-07-21  7:38   ` Michael Ellerman

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