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  1. 19 Jan, 2018 5 commits
  3. 16 Oct, 2017 1 commit
  5. 20 Jun, 2017 5 commits
  7. 19 Jun, 2017 1 commit
  9. 28 Apr, 2017 5 commits
  11. 23 Apr, 2017 2 commits
  13. 20 Apr, 2017 1 commit
    • Nicholas Piggin's avatar
      powerpc/64s: Use relon prolog for EXC_VIRT_OOL_MASKABLE_HV handlers · a050d20d
      Nicholas Piggin authored 
      Hypervisor Virtualization and Directed Hypervisor Doorbell interrupt handlers
use the macro EXC_VIRT_OOL_MASKABLE_HV for their relocation-on handlers, which
calls MASKABLE_RELON_EXCEPTION_HV_OOL, which uses the *real mode* interrupt
prolog. This means we needlessly rfid from virtual mode to virtual mode.

For POWER8 it only affects doorbell IPIs. Context switch microbenchmark between
threads with snooze disabled (which causes IPI) gets about 3% faster, about 370
cycles. Should be more important on POWER9 with global doorbells and HVI for
host interrupts.

Use the RELON variant instead to reduce overhead.

Fixes: 1707dd16 ("powerpc: Save CFAR before branching in interrupt entry paths")
Signed-off-by: default avatarNicholas Piggin <npiggin@gmail.com>
[mpe: Fold some more detail into the change log]
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      a050d20d
  15. 18 Apr, 2017 1 commit
    • Michael Ellerman's avatar
      powerpc/64: Fix HMI exception on LE with CONFIG_RELOCATABLE=y · be5c5e84
      Michael Ellerman authored 
      Prior to commit 2337d207 ("powerpc/64: CONFIG_RELOCATABLE support for hmi
interrupts"), the branch from hmi_exception_early() to hmi_exception_realmode()
was just a bl hmi_exception_realmode, which the linker would turn into a bl to
the local entry point of hmi_exception_realmode. This was broken when
CONFIG_RELOCATABLE=y because hmi_exception_realmode() is not in the low part of
the kernel text that is copied down to 0x0.

But in fixing that, we added a new bug on little endian kernels. Because the
branch is now a bctrl when CONFIG_RELOCATABLE=y, we branch to the global entry
point of hmi_exception_realmode(). The global entry point must be called with
r12 containing the address of hmi_exception_realmode(), because it uses that
value to calculate the TOC value (r2).

This may manifest as a checkstop, because we take a junk value from r12 which
came from HSRR1, add a small constant to it and then use that as the TOC
pointer. The HSRR1 value will have 0x9 as the top nibble, which puts it above
RAM and somewhere in MMIO space.

Fix it by changing the BRANCH_LINK_TO_FAR() macro to always use r12 to load the
label we're branching to. This means r12 will be setup correctly on LE, fixing
this bug, and r12 is also volatile across function calls on BE so it's a good
choice anyway.

Fixes: 2337d207 ("powerpc/64: CONFIG_RELOCATABLE support for hmi interrupts")
Reported-by: default avatarMahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Acked-by: default avatarNicholas Piggin <npiggin@gmail.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      be5c5e84
  17. 07 Feb, 2017 1 commit
  19. 31 Jan, 2017 2 commits
    • Paul Mackerras's avatar
      powerpc/64: Allow for relocation-on interrupts from guest to host · bc355125
      Paul Mackerras authored 
      With host and guest both using radix translation, it is feasible
for the host to take interrupts that come from the guest with
relocation on, and that is in fact what the POWER9 hardware will
do when LPCR[AIL] = 3.  All such interrupts use HSRR0/1 not SRR0/1
except for system call with LEV=1 (hcall).

Therefore this adds the KVM tests to the _HV variants of the
relocation-on interrupt handlers, and adds the KVM test to the
relocation-on system call entry point.

We also instantiate the relocation-on versions of the hypervisor
data storage and instruction interrupt handlers, since these can
occur with relocation on in radix guests.
Signed-off-by: default avatarPaul Mackerras <paulus@ozlabs.org>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      bc355125
    • Nicholas Piggin's avatar
      KVM: PPC: Book3S: 64-bit CONFIG_RELOCATABLE support for interrupts · a97a65d5
      Nicholas Piggin authored 
      64-bit Book3S exception handlers must find the dynamic kernel base
to add to the target address when branching beyond __end_interrupts,
in order to support kernel running at non-0 physical address.

Support this in KVM by branching with CTR, similarly to regular
interrupt handlers. The guest CTR saved in HSTATE_SCRATCH1 and
restored after the branch.

Without this, the host kernel hangs and crashes randomly when it is
running at a non-0 address and a KVM guest is started.
Signed-off-by: default avatarNicholas Piggin <npiggin@gmail.com>
Acked-by: default avatarPaul Mackerras <paulus@ozlabs.org>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      a97a65d5
  21. 27 Jan, 2017 1 commit
  23. 12 Nov, 2016 2 commits
    • Hugh Dickins's avatar
      powerpc: Fix exception vector build with 2.23 era binutils · e6740ae6
      Hugh Dickins authored 
      The changes to use gas sections for constructing the exception vectors
causes a build break when using binutils 2.23:

  arch/powerpc/kernel/exceptions-64s.S:770: Error: operand out of range
  (0xffffffffffff8100 is not between 0x0000000000000000 and 0x000000000000ffff)

And so on.

Reported by Hugh with binutils-2.23.2-8.1.4.ppc64 from openSUSE 13.1 and
also Naveen & Denis using 2.23.52.0.1-26.el7 from RHEL 7. Strangely
binutils 2.22 (what I test with) is not affected.

This is caused by the use of @l in LOAD_HANDLER(). The @l was only
recently added in commit a24553dd ("powerpc/pseries: Remove
unnecessary syscall trampoline").

Luckily the gas section changes split out the LOAD_SYSCALL_HANDLER()
macro, which means we actually *don't* need to use @l in LOAD_HANDLER()
any more, only in LOAD_SYSCALL_HANDLER().

So drop the @l from LOAD_HANDLER().

Fixes: 57f26649 ("powerpc: Use gas sections for arranging exception vectors")
Signed-off-by: default avatarHugh Dickins <hughd@google.com>
[mpe: Add gory details to change log]
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      e6740ae6
    • Nicholas Piggin's avatar
      powerpc/64s: Fix system reset interrupt winkle wakeups · f23ed166
      Nicholas Piggin authored 
      Wakeups from winkle set the low bit of the HSPRG0 register, to
distinguish it from other sleep states. This is also the PACA pointer.
The system reset exception handler fails to mask this bit away before
using this value before using it as the PACA pointer.

Fix this by adding a new type of exception prolog macro where we already
have the PACA set in r13, and have the system reset vector mask it out.
The winkle wakeup handler will store the masked value back into HSPRG0.

Fixes: fb479e44 ("powerpc/64s: relocation, register save fixes for system reset interrupt")
Cc: stable@vger.kernel.org # v3.0+
Signed-off-by: default avatarNicholas Piggin <npiggin@gmail.com>
Reviewed-by: default avatarMahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      f23ed166
  25. 27 Oct, 2016 1 commit
    • Nicholas Piggin's avatar
      powerpc/64s: relocation, register save fixes for system reset interrupt · fb479e44
      Nicholas Piggin authored 
      This patch does a couple of things. First of all, powernv immediately
explodes when running a relocated kernel, because the system reset
exception for handling sleeps does not do correct relocated branches.

Secondly, the sleep handling code trashes the condition and cfar
registers, which we would like to preserve for debugging purposes (for
non-sleep case exception).

This patch changes the exception to use the standard format that saves
registers before any tests or branches are made. It adds the test for
idle-wakeup as an "extra" to break out of the normal exception path.
Then it branches to a relocated idle handler that calls the various
idle handling functions.

After this patch, POWER8 CPU simulator now boots powernv kernel that is
running at non-zero.

Fixes: 948cf67c ("powerpc: Add NAP mode support on Power7 in HV mode")
Cc: stable@vger.kernel.org # v3.0+
Signed-off-by: default avatarNicholas Piggin <npiggin@gmail.com>
Acked-by: default avatarGautham R. Shenoy <ego@linux.vnet.ibm.com>
Acked-by: default avatarBalbir Singh <bsingharora@gmail.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      fb479e44
  27. 04 Oct, 2016 2 commits
    • Nicholas Piggin's avatar
      powerpc: Use gas sections for arranging exception vectors · 57f26649
      Nicholas Piggin authored 
      Use assembler sections of fixed size and location to arrange the 64-bit
Book3S exception vector code (64-bit Book3E also uses it in head_64.S
for 0x0..0x100).

This allows better flexibility in arranging exception code and hiding
unimportant details behind macros.

Gas sections can be a bit painful to use this way, mainly because the
assembler does not know where they will be finally linked. Taking
absolute addresses requires a bit of trickery for example, but it can
be hidden behind macros for the most part.

Generated code is mostly the same except locations, offsets, alignments.

The "+ 0x2" is only required for the trap number / kvm exit number,
which gets loaded as a constant into a register.

Previously, code also used + 0x2 for label names, but we changed to
using "H" to distinguish HV case for that. Remove the last vestiges
of that.

__after_prom_start is taking absolute address of a label in another
fixed section. Newer toolchains seemed to compile this okay, but older
ones do not. FIXED_SYMBOL_ABS_ADDR is more foolproof, it just takes an
additional line to define.
Signed-off-by: default avatarNicholas Piggin <npiggin@gmail.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      57f26649
    • Michael Ellerman's avatar
      powerpc/64s: Add new exception vector macros · da2bc464
      Michael Ellerman authored 
      Create arch/powerpc/include/asm/head-64.h with macros that specify
an exception vector (name, type, location), which will be used to
label and lay out exceptions into the object file.

Naming is moved out of exception-64s.h, which is used to specify the
implementation of exception handlers.

objdump of generated code in exception vectors is unchanged except for
names. Alignment directives scattered around are annoying, but done
this way so that disassembly can verify identical instruction
generation before and after patch. These get cleaned up in future
patch.

We change the way KVMTEST works, explicitly passing EXC_HV or EXC_STD
rather than overloading the trap number. This removes the need to have
SOFTEN values for the overloaded trap numbers, eg. 0x502.
Signed-off-by: default avatarNicholas Piggin <npiggin@gmail.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      da2bc464
  29. 22 Sep, 2016 1 commit
    • Nicholas Piggin's avatar
      powerpc/pseries: Remove unnecessary syscall trampoline · a24553dd
      Nicholas Piggin authored 
      When we originally added the ability to split the exception vectors from
the kernel (commit 1f6a93e4 ("powerpc: Make it possible to move the
interrupt handlers away from the kernel" 2008-09-15)), the LOAD_HANDLER() macro
used an addi instruction to compute the offset of the common handler
from the kernel base address.

Using addi meant the handler had to be within 32K of the kernel base
address, due to the addi instruction taking a signed immediate value.
That necessitated creating a trampoline for the system call handler,
because system_call_common (in entry64.S) is not linked within 32K of
the kernel base address.

Later in commit 61e2390e ("powerpc: Make load_hander handle upto 64k
offset" 2012-11-15) we changed LOAD_HANDLER to take a 64K offset, by
changing it to use ori.

Although system_call_common is not in head_64.S or exceptions-64s.S, it
is included in head-y, which causes it to be linked early in the kernel
text, so in practice it ends up below 64K. Additionally if it can't be
placed below 64K the linker will fail to build with a "relocation
truncated to fit" error.

So remove the trampoline.

Newer toolchains are able to work out that the ori in LOAD_HANDLER only
takes a 16 bit offset, and so they generate a 16 bit relocation. Older
toolchains (binutils 2.22 at least) are not so smart, so we have to add
the @l annotation to tell the assembler to generate a 16 bit relocation.
Signed-off-by: default avatarNicholas Piggin <npiggin@gmail.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      a24553dd
  31. 13 Sep, 2016 2 commits
  33. 17 Jul, 2016 1 commit
  35. 09 Jul, 2016 1 commit
  37. 17 Dec, 2015 2 commits
    • Michael Ellerman's avatar
      powerpc/kernel: Combine vec/loc for STD_EXCEPTION_PSERIES · 2613265c
      Michael Ellerman authored 
      The STD_EXCEPTION_PSERIES macro takes both a vector number, and a
location (memory address). However both are always identical, so combine
them to save repeating ourselves.

This does mean an exception handler must always exist at the location in
memory that matches its vector number. But that's OK because this is the
"STD" macro (standard), which does exactly that. We have other macros
for the other cases, eg. STD_EXCEPTION_PSERIES_OOL (out of line).
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      2613265c
    • Michael Ellerman's avatar
      powerpc/kernel: Drop HMT_MEDIUM_PPR_DISCARD · d6265aea
      Michael Ellerman authored 
      HMT_MEDIUM_PPR_DISCARD is a macro which is present at the start of most
of our first level exception handlers. It conditionally executes a
HMT_MEDIUM instruction, which sets the processor priority to medium.

On on modern systems, ie. Power7 and later, it is nop'ed out at boot.
All it does is make the exception vectors more cramped, and consume 4
bytes of icache.

On old systems it has the effect of boosting the processor priority at
the start of exception processing. If we were previously in the idle
loop for example, we may be at low or very low priority. This is
desirable as we want to process the exception as fast as possible.

However looking closely at the generated code, we see that in all cases
we execute another HMT_MEDIUM just four instructions later. With code
patching applied, the final code on an old (Power6) system will look
like, eg:

  c000000000000300 <data_access_pSeries>:
  c000000000000300:	7c 42 13 78	mr	r2,r2		<-
  c000000000000304:	7d b2 43 a6	mtsprg	2,r13
  c000000000000308:	7d b1 42 a6	mfsprg	r13,1
  c00000000000030c:	f9 2d 00 80	std	r9,128(r13)
  c000000000000310:	60 00 00 00	nop
  c000000000000314:	7c 42 13 78	mr	r2,r2		<-

So I suggest that the added code complexity of HMT_MEDIUM_PPR_DISCARD is
not justified by the benefit of boosting the processor priority for the
duration of four instructions, and therefore we drop it.
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      d6265aea
  39. 01 Dec, 2015 1 commit
    • Paul Mackerras's avatar
      powerpc/64: Include KVM guest test in all interrupt vectors · 31a40e2b
      Paul Mackerras authored 
      Currently, if HV KVM is configured but PR KVM isn't, we don't include
a test to see whether we were interrupted in KVM guest context for the
set of interrupts which get delivered directly to the guest by hardware
if they occur in the guest.  This includes things like program
interrupts.

However, the recent bug where userspace could set the MSR for a VCPU
to have an illegal value in the TS field, and thus cause a TM Bad Thing
type of program interrupt on the hrfid that enters the guest, showed that
we can never be completely sure that these interrupts can never occur
in the guest entry/exit code.  If one of these interrupts does happen
and we have HV KVM configured but not PR KVM, then we end up trying to
run the handler in the host with the MMU set to the guest MMU context,
which generally ends badly.

Thus, for robustness it is better to have the test in every interrupt
vector, so that if some way is found to trigger some interrupt in the
guest entry/exit path, we can handle it without immediately crashing
the host.

This means that the distinction between KVMTEST and KVMTEST_PR goes
away.  Thus we delete KVMTEST_PR and associated macros and use KVMTEST
everywhere that we previously used either KVMTEST_PR or KVMTEST.  It
also means that SOFTEN_TEST_HV_201 becomes the same as SOFTEN_TEST_PR,
so we deleted SOFTEN_TEST_HV_201 and use SOFTEN_TEST_PR instead.
Signed-off-by: default avatarPaul Mackerras <paulus@samba.org>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      31a40e2b
  41. 05 Aug, 2014 1 commit
  43. 28 Jul, 2014 1 commit
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