powerpc/time: add API for KVM to re-arm the host timer/decrementer

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Rather than have KVM look up the host timer and fiddle with the
irq-work internal details, have the powerpc/time.c code provide a
function for KVM to re-arm the Linux timer code when exiting a
guest.

This is implementation has an improvement over existing code of
marking a decrementer interrupt as soft-pending if a timer has
expired, rather than setting DEC to a -ve value, which tended to
cause host timers to take two interrupts (first hdec to exit the
guest, then the immediate dec).

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211123095231.1036501-8-npiggin@gmail.com

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Nicholas Piggin 2021-11-23 19:51:45 +10:00 • committed by Michael Ellerman

parent 34bf08a207

commit 25aa145856

3 changed files with 49 additions and 26 deletions

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16

arch/powerpc/include/asm/time.h

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52

arch/powerpc/kernel/time.c

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7

arch/powerpc/kvm/book3s_hv.c

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