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commit: 14561011b6e2f7e5a3d62ad4e7565fec4f326512 |
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Author: Georgy Yakovlev <gyakovlev <AT> gentoo <DOT> org> |
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AuthorDate: Thu Jul 8 02:09:36 2021 +0000 |
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Commit: Georgy Yakovlev <gyakovlev <AT> gentoo <DOT> org> |
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CommitDate: Thu Jul 8 02:12:19 2021 +0000 |
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URL: https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=14561011 |
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|
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sys-kernel/gentoo-kernel: add power9 kvm patch to 5.10.47 |
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|
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Signed-off-by: Georgy Yakovlev <gyakovlev <AT> gentoo.org> |
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|
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.../gentoo-kernel/files/5.10.47-ppc64-kvm.patch | 56 ++++++++++++++++++++++ |
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.../gentoo-kernel/gentoo-kernel-5.10.47.ebuild | 1 + |
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2 files changed, 57 insertions(+) |
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|
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diff --git a/sys-kernel/gentoo-kernel/files/5.10.47-ppc64-kvm.patch b/sys-kernel/gentoo-kernel/files/5.10.47-ppc64-kvm.patch |
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new file mode 100644 |
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index 00000000000..59a7c7e7581 |
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--- /dev/null |
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+++ b/sys-kernel/gentoo-kernel/files/5.10.47-ppc64-kvm.patch |
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@@ -0,0 +1,56 @@ |
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+From 25edcc50d76c834479d11fcc7de46f3da4d95121 Mon Sep 17 00:00:00 2001 |
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+From: Fabiano Rosas <farosas@×××××××××.com> |
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+Date: Thu, 4 Feb 2021 17:05:17 -0300 |
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+Subject: [PATCH] KVM: PPC: Book3S HV: Save and restore FSCR in the P9 path |
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+ |
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+The Facility Status and Control Register is a privileged SPR that |
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+defines the availability of some features in problem state. Since it |
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+can be written by the guest, we must restore it to the previous host |
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+value after guest exit. |
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+ |
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+This restoration is currently done by taking the value from |
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+current->thread.fscr, which in the P9 path is not enough anymore |
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+because the guest could context switch the QEMU thread, causing the |
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+guest-current value to be saved into the thread struct. |
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+ |
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+The above situation manifested when running a QEMU linked against a |
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+libc with System Call Vectored support, which causes scv |
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+instructions to be run by QEMU early during the guest boot (during |
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+SLOF), at which point the FSCR is 0 due to guest entry. After a few |
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+scv calls (1 to a couple hundred), the context switching happens and |
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+the QEMU thread runs with the guest value, resulting in a Facility |
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+Unavailable interrupt. |
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+ |
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+This patch saves and restores the host value of FSCR in the inner |
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+guest entry loop in a way independent of current->thread.fscr. The old |
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+way of doing it is still kept in place because it works for the old |
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+entry path. |
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+ |
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+Signed-off-by: Fabiano Rosas <farosas@×××××××××.com> |
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+Signed-off-by: Paul Mackerras <paulus@××××××.org> |
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+--- |
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+ arch/powerpc/kvm/book3s_hv.c | 4 ++++ |
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+ 1 file changed, 4 insertions(+) |
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+ |
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+diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c |
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+index 89c686c17f0606..f6d470157fcb62 100644 |
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+--- a/arch/powerpc/kvm/book3s_hv.c |
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++++ b/arch/powerpc/kvm/book3s_hv.c |
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+@@ -3611,6 +3611,7 @@ static int kvmhv_p9_guest_entry(struct kvm_vcpu *vcpu, u64 time_limit, |
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+ unsigned long host_tidr = mfspr(SPRN_TIDR); |
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+ unsigned long host_iamr = mfspr(SPRN_IAMR); |
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+ unsigned long host_amr = mfspr(SPRN_AMR); |
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++ unsigned long host_fscr = mfspr(SPRN_FSCR); |
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+ s64 dec; |
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+ u64 tb; |
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+ int trap, save_pmu; |
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+@@ -3751,6 +3752,9 @@ static int kvmhv_p9_guest_entry(struct kvm_vcpu *vcpu, u64 time_limit, |
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+ if (host_amr != vcpu->arch.amr) |
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+ mtspr(SPRN_AMR, host_amr); |
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+ |
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++ if (host_fscr != vcpu->arch.fscr) |
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++ mtspr(SPRN_FSCR, host_fscr); |
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++ |
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+ msr_check_and_set(MSR_FP | MSR_VEC | MSR_VSX); |
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+ store_fp_state(&vcpu->arch.fp); |
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+ #ifdef CONFIG_ALTIVEC |
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|
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diff --git a/sys-kernel/gentoo-kernel/gentoo-kernel-5.10.47.ebuild b/sys-kernel/gentoo-kernel/gentoo-kernel-5.10.47.ebuild |
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index 484c3c53d62..85ca3ef0d12 100644 |
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--- a/sys-kernel/gentoo-kernel/gentoo-kernel-5.10.47.ebuild |
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+++ b/sys-kernel/gentoo-kernel/gentoo-kernel-5.10.47.ebuild |
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@@ -55,6 +55,7 @@ src_prepare() { |
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local PATCHES=( |
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# meh, genpatches have no directory |
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"${WORKDIR}"/*.patch |
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+ "${FILESDIR}"/5.10.47-ppc64-kvm.patch |
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) |
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default |