From 94ffba484663ab3fc695ce2a34871e8c3db499f7 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= Date: Sun, 15 Jul 2018 17:43:11 +0200 Subject: x86/kvmclock: set pvti_cpu0_va after enabling kvmclock MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit pvti_cpu0_va is the address of shared kvmclock data structure. pvti_cpu0_va is currently kept unset (1) on 32 bit systems, (2) when kvmclock vsyscall is disabled, and (3) if kvmclock is not stable. This poses a problem, because kvm_ptp needs pvti_cpu0_va, but (1) can work on 32 bit, (2) has little relation to the vsyscall, and (3) does not need stable kvmclock (although kvmclock won't be used for system clock if it's not stable, so kvm_ptp is pointless in that case). Expose pvti_cpu0_va whenever kvmclock is enabled to allow all users to work with it. This fixes a regression found on Gentoo: https://bugs.gentoo.org/658544. Fixes: 9f08890ab906 ("x86/pvclock: add setter for pvclock_pvti_cpu0_va") Cc: stable@vger.kernel.org Reported-by: Andreas Steinmetz Signed-off-by: Radim Krčmář Signed-off-by: Paolo Bonzini --- arch/x86/kernel/kvmclock.c | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-) (limited to 'arch/x86/kernel/kvmclock.c') diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c index 8b26c9e01cc4..d79a18b4cf9d 100644 --- a/arch/x86/kernel/kvmclock.c +++ b/arch/x86/kernel/kvmclock.c @@ -319,6 +319,8 @@ void __init kvmclock_init(void) printk(KERN_INFO "kvm-clock: Using msrs %x and %x", msr_kvm_system_time, msr_kvm_wall_clock); + pvclock_set_pvti_cpu0_va(hv_clock); + if (kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE_STABLE_BIT)) pvclock_set_flags(PVCLOCK_TSC_STABLE_BIT); @@ -366,14 +368,11 @@ int __init kvm_setup_vsyscall_timeinfo(void) vcpu_time = &hv_clock[cpu].pvti; flags = pvclock_read_flags(vcpu_time); - if (!(flags & PVCLOCK_TSC_STABLE_BIT)) { - put_cpu(); - return 1; - } - - pvclock_set_pvti_cpu0_va(hv_clock); put_cpu(); + if (!(flags & PVCLOCK_TSC_STABLE_BIT)) + return 1; + kvm_clock.archdata.vclock_mode = VCLOCK_PVCLOCK; #endif return 0; -- cgit v1.2.3 From e10f7805032365cc11c739a97f226ebb48aee042 Mon Sep 17 00:00:00 2001 From: Peng Hao Date: Sat, 14 Jul 2018 23:28:29 +0800 Subject: kvmclock: fix TSC calibration for nested guests Inside a nested guest, access to hardware can be slow enough that tsc_read_refs always return ULLONG_MAX, causing tsc_refine_calibration_work to be called periodically and the nested guest to spend a lot of time reading the ACPI timer. However, if the TSC frequency is available from the pvclock page, we can just set X86_FEATURE_TSC_KNOWN_FREQ and avoid the recalibration. 'refine' operation. Suggested-by: Peter Zijlstra Signed-off-by: Peng Hao [Commit message rewritten. - Paolo] Signed-off-by: Paolo Bonzini --- arch/x86/kernel/kvmclock.c | 1 + 1 file changed, 1 insertion(+) (limited to 'arch/x86/kernel/kvmclock.c') diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c index d79a18b4cf9d..4c53d12ca933 100644 --- a/arch/x86/kernel/kvmclock.c +++ b/arch/x86/kernel/kvmclock.c @@ -138,6 +138,7 @@ static unsigned long kvm_get_tsc_khz(void) src = &hv_clock[cpu].pvti; tsc_khz = pvclock_tsc_khz(src); put_cpu(); + setup_force_cpu_cap(X86_FEATURE_TSC_KNOWN_FREQ); return tsc_khz; } -- cgit v1.2.3