[PATCH v2 14/23] MIPS: KVM: Override guest kernel timer frequency directly

James Hogan
2014-05-29T09:17:08Z

The KVM_HOST_FREQ Kconfig symbol was used by KVM guest kernels to
override the timer frequency calculation to a value based on the host
frequency. Now that the KVM timer emulation is implemented independent
of the host timer frequency and defaults to 100MHz, adjust the working
of CONFIG_KVM_HOST_FREQ to match.

The Kconfig symbol now specifies the guest timer frequency directly, and
has been renamed accordingly to KVM_GUEST_TIMER_FREQ. It now defaults to
100MHz too and the help text is updated to make it clear that a zero
value will allow the normal timer frequency calculation to take place
(based on the emulated RTC).

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Gleb Natapov <gleb@kernel.org>
Cc: kvm@vger.kernel.org
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: Sanjay Lal <sanjayl@kymasys.com>
---
arch/mips/Kconfig | 12 ++++++------
arch/mips/mti-malta/malta-time.c | 14 ++------------
2 files changed, 8 insertions(+), 18 deletions(-)

diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 5cd695f905a1..5e0014e864f3 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -1756,14 +1756,14 @@ config KVM_GUEST
help
Select this option if building a guest kernel for KVM (Trap & Emulate) mode

-config KVM_HOST_FREQ
- int "KVM Host Processor Frequency (MHz)"
+config KVM_GUEST_TIMER_FREQ
+ int "Count/Compare Timer Frequency (MHz)"
depends on KVM_GUEST
- default 500
+ default 100
help
- Select this option if building a guest kernel for KVM to skip
- RTC emulation when determining guest CPU Frequency. Instead, the guest
- processor frequency is automatically derived from the host frequency.
+ Set this to non-zero if building a guest kernel for KVM to skip RTC
+ emulation when determining guest CPU Frequency. Instead, the guest's
+ timer frequency is specified directly.

choice
prompt "Kernel page size"
diff --git a/arch/mips/mti-malta/malta-time.c b/arch/mips/mti-malta/malta-time.c
index 319009912142..3778a359f3ad 100644
--- a/arch/mips/mti-malta/malta-time.c
+++ b/arch/mips/mti-malta/malta-time.c
@@ -74,18 +74,8 @@ static void __init estimate_frequencies(void)
unsigned int giccount = 0, gicstart = 0;
#endif

-#if defined (CONFIG_KVM_GUEST) && defined (CONFIG_KVM_HOST_FREQ)
- unsigned int prid = read_c0_prid() & (PRID_COMP_MASK | PRID_IMP_MASK);
-
- /*
- * XXXKYMA: hardwire the CPU frequency to Host Freq/4
- */
- count = (CONFIG_KVM_HOST_FREQ * 1000000) >> 3;
- if ((prid != (PRID_COMP_MIPS | PRID_IMP_20KC)) &&
- (prid != (PRID_COMP_MIPS | PRID_IMP_25KF)))
- count *= 2;
-
- mips_hpt_frequency = count;
+#if defined(CONFIG_KVM_GUEST) && CONFIG_KVM_GUEST_TIMER_FREQ
+ mips_hpt_frequency = CONFIG_KVM_GUEST_TIMER_FREQ * 1000000;
return;
#endif

--
1.9.3