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[PATCH 4.9 12/44] KVM: PPC: Book3S HV: Preserve userspace HTM state properly

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4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Paul Mackerras <paulus@ozlabs.org>

commit 46a704f8409f79fd66567ad3f8a7304830a84293 upstream.

If userspace attempts to call the KVM_RUN ioctl when it has hardware
transactional memory (HTM) enabled, the values that it has put in the
HTM-related SPRs TFHAR, TFIAR and TEXASR will get overwritten by
guest values.  To fix this, we detect this condition and save those
SPR values in the thread struct, and disable HTM for the task.  If
userspace goes to access those SPRs or the HTM facility in future,
a TM-unavailable interrupt will occur and the handler will reload
those SPRs and re-enable HTM.

If userspace has started a transaction and suspended it, we would
currently lose the transactional state in the guest entry path and
would almost certainly get a "TM Bad Thing" interrupt, which would
cause the host to crash.  To avoid this, we detect this case and
return from the KVM_RUN ioctl with an EINVAL error, with the KVM
exit reason set to KVM_EXIT_FAIL_ENTRY.

Fixes: b005255e12a3 ("KVM: PPC: Book3S HV: Context-switch new POWER8 SPRs", 2014-01-08)
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/powerpc/kvm/book3s_hv.c |   21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -2813,6 +2813,27 @@ static int kvmppc_vcpu_run_hv(struct kvm
 		return -EINVAL;
 	}
 
+	/*
+	 * Don't allow entry with a suspended transaction, because
+	 * the guest entry/exit code will lose it.
+	 * If the guest has TM enabled, save away their TM-related SPRs
+	 * (they will get restored by the TM unavailable interrupt).
+	 */
+#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
+	if (cpu_has_feature(CPU_FTR_TM) && current->thread.regs &&
+	    (current->thread.regs->msr & MSR_TM)) {
+		if (MSR_TM_ACTIVE(current->thread.regs->msr)) {
+			run->exit_reason = KVM_EXIT_FAIL_ENTRY;
+			run->fail_entry.hardware_entry_failure_reason = 0;
+			return -EINVAL;
+		}
+		current->thread.tm_tfhar = mfspr(SPRN_TFHAR);
+		current->thread.tm_tfiar = mfspr(SPRN_TFIAR);
+		current->thread.tm_texasr = mfspr(SPRN_TEXASR);
+		current->thread.regs->msr &= ~MSR_TM;
+	}
+#endif
+
 	kvmppc_core_prepare_to_enter(vcpu);
 
 	/* No need to go into the guest when all we'll do is come back out */

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[PATCH 4.9 00/44] 4.9.35-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-06-27 16:20 +0200
  [PATCH 4.9 16/44] HID: Add quirk for Dell PIXART OEM mouse Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-06-27 16:20 +0200
  [PATCH 4.9 14/44] CIFS: Improve readdir verbosity Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-06-27 16:20 +0200
  [PATCH 4.9 42/44] net: phy: fix marvell phy status reading Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-06-27 16:20 +0200
  [PATCH 4.9 10/44] perf/x86/intel: Add 1G DTLB load/store miss support for SKL Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-06-27 16:20 +0200
  [PATCH 4.9 07/44] powerpc/perf: Fix oops when kthread execs user process Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-06-27 16:20 +0200
  [PATCH 4.9 11/44] KVM: s390: gaccess: fix real-space designation asce handling for gmap shadows Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-06-27 16:20 +0200
  [PATCH 4.9 21/44] brcmfmac: add parameter to pass error code in firmware callback Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-06-27 16:20 +0200
  [PATCH 4.9 37/44] usb: gadget: f_fs: avoid out of bounds access on comp_desc Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-06-27 16:20 +0200
  [PATCH 4.9 15/44] cxgb4: notify uP to route ctrlq compl to rdma rspq Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-06-27 16:20 +0200
  [PATCH 4.9 35/44] of: Add check to of_scan_flat_dt() before accessing initial_boot_params Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-06-27 16:40 +0200
  [PATCH 4.9 06/44] fs/exec.c: account for argv/envp pointers Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-06-27 16:40 +0200
  [PATCH 4.9 27/44] target: Fix kref->refcount underflow in transport_cmd_finish_abort Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-06-27 16:40 +0200
  [PATCH 4.9 12/44] KVM: PPC: Book3S HV: Preserve userspace HTM state properly Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-06-27 16:40 +0200
  [PATCH 4.9 03/44] xen-blkback: dont leak stack data via response ring Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-06-27 16:40 +0200
  [PATCH 4.9 09/44] lib/cmdline.c: fix get_options() overflow while parsing ranges Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-06-27 16:40 +0200
  [PATCH 4.9 23/44] brcmfmac: unbind all devices upon failure in firmware callback Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-06-27 16:40 +0200
  [PATCH 4.9 38/44] rt2x00: avoid introducing a USB dependency in the rt2x00lib module Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-06-27 16:40 +0200
  [PATCH 4.9 28/44] iscsi-target: Fix delayed logout processing greater than SECONDS_FOR_LOGOUT_COMP Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-06-27 16:40 +0200
  [PATCH 4.9 05/44] ALSA: pcm: Dont treat NULL chmap as a fatal error Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-06-27 16:40 +0200
  [PATCH 4.9 30/44] drm/radeon: add a PX quirk for another K53TK variant Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-06-27 16:40 +0200
  [PATCH 4.9 26/44] arm64/vdso: Fix nsec handling for CLOCK_MONOTONIC_RAW Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-06-27 16:40 +0200
  [PATCH 4.9 22/44] brcmfmac: use firmware callback upon failure to load Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-06-27 16:40 +0200
  [PATCH 4.9 04/44] ALSA: firewire-lib: Fix stall of process context at packet error Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-06-27 16:40 +0200
  [PATCH 4.9 08/44] autofs: sanity check status reported with AUTOFS_DEV_IOCTL_FAIL Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-06-27 16:40 +0200
  [PATCH 4.9 40/44] dmaengine: bcm2835: Fix cyclic DMA period splitting Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-06-27 16:40 +0200
  [PATCH 4.9 31/44] drm/radeon: add a quirk for Toshiba Satellite L20-183 Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-06-27 16:40 +0200
  [PATCH 4.9 19/44] powerpc/64s: Handle data breakpoints in Radix mode Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-06-27 16:40 +0200
  [PATCH 4.9 39/44] net: phy: Initialize mdio clock at probe function Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-06-27 16:40 +0200
  [PATCH 4.9 25/44] time: Fix CLOCK_MONOTONIC_RAW sub-nanosecond accounting Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-06-27 16:40 +0200
  [PATCH 4.9 29/44] iscsi-target: Reject immediate data underflow larger than SCSI transfer length Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-06-27 16:40 +0200
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  Re: [PATCH 4.9 00/44] 4.9.35-stable review Sumit Semwal <sumit.semwal@linaro.org> - 2017-06-27 19:40 +0200
    Re: [PATCH 4.9 00/44] 4.9.35-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-06-28 14:10 +0200
  Re: [PATCH 4.9 00/44] 4.9.35-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-06-27 20:40 +0200
  Re: [PATCH 4.9 00/44] 4.9.35-stable review Guenter Roeck <linux@roeck-us.net> - 2017-06-27 21:10 +0200
  Re: [PATCH 4.9 00/44] 4.9.35-stable review Shuah Khan <shuahkh@osg.samsung.com> - 2017-06-28 16:00 +0200

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