diff options
Diffstat (limited to '0001-x86-hyperv-Suspend-resume-the-VP-assist-page-for-hib.patch')
| -rw-r--r-- | 0001-x86-hyperv-Suspend-resume-the-VP-assist-page-for-hib.patch | 92 |
1 files changed, 0 insertions, 92 deletions
diff --git a/0001-x86-hyperv-Suspend-resume-the-VP-assist-page-for-hib.patch b/0001-x86-hyperv-Suspend-resume-the-VP-assist-page-for-hib.patch deleted file mode 100644 index be667bd95..000000000 --- a/0001-x86-hyperv-Suspend-resume-the-VP-assist-page-for-hib.patch +++ /dev/null @@ -1,92 +0,0 @@ -From 421f090c819d695942a470051cd624dc43deaf95 Mon Sep 17 00:00:00 2001 -From: Dexuan Cui <decui@microsoft.com> -Date: Mon, 20 Apr 2020 19:46:11 -0700 -Subject: [PATCH] x86/hyperv: Suspend/resume the VP assist page for hibernation - -Unlike the other CPUs, CPU0 is never offlined during hibernation, so in the -resume path, the "new" kernel's VP assist page is not suspended (i.e. not -disabled), and later when we jump to the "old" kernel, the page is not -properly re-enabled for CPU0 with the allocated page from the old kernel. - -So far, the VP assist page is used by hv_apic_eoi_write(), and is also -used in the case of nested virtualization (running KVM atop Hyper-V). - -For hv_apic_eoi_write(), when the page is not properly re-enabled, -hvp->apic_assist is always 0, so the HV_X64_MSR_EOI MSR is always written. -This is not ideal with respect to performance, but Hyper-V can still -correctly handle this according to the Hyper-V spec; nevertheless, Linux -still must update the Hyper-V hypervisor with the correct VP assist page -to prevent Hyper-V from writing to the stale page, which causes guest -memory corruption and consequently may have caused the hangs and triple -faults seen during non-boot CPUs resume. - -Fix the issue by calling hv_cpu_die()/hv_cpu_init() in the syscore ops. -Without the fix, hibernation can fail at a rate of 1/300 ~ 1/500. -With the fix, hibernation can pass a long-haul test of 2000 runs. - -In the case of nested virtualization, disabling/reenabling the assist -page upon hibernation may be unsafe if there are active L2 guests. -It looks KVM should be enhanced to abort the hibernation request if -there is any active L2 guest. - -Fixes: 05bd330a7fd8 ("x86/hyperv: Suspend/resume the hypercall page for hibernation") -Cc: stable@vger.kernel.org -Signed-off-by: Dexuan Cui <decui@microsoft.com> -Link: https://lore.kernel.org/r/1587437171-2472-1-git-send-email-decui@microsoft.com -Signed-off-by: Wei Liu <wei.liu@kernel.org> ---- - arch/x86/hyperv/hv_init.c | 12 ++++++++++-- - 1 file changed, 10 insertions(+), 2 deletions(-) - -diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c -index 624f5d9b0f79..fd51bac11b46 100644 ---- a/arch/x86/hyperv/hv_init.c -+++ b/arch/x86/hyperv/hv_init.c -@@ -73,7 +73,8 @@ static int hv_cpu_init(unsigned int cpu) - struct page *pg; - - input_arg = (void **)this_cpu_ptr(hyperv_pcpu_input_arg); -- pg = alloc_page(GFP_KERNEL); -+ /* hv_cpu_init() can be called with IRQs disabled from hv_resume() */ -+ pg = alloc_page(irqs_disabled() ? GFP_ATOMIC : GFP_KERNEL); - if (unlikely(!pg)) - return -ENOMEM; - *input_arg = page_address(pg); -@@ -254,6 +255,7 @@ static int __init hv_pci_init(void) - static int hv_suspend(void) - { - union hv_x64_msr_hypercall_contents hypercall_msr; -+ int ret; - - /* - * Reset the hypercall page as it is going to be invalidated -@@ -270,12 +272,17 @@ static int hv_suspend(void) - hypercall_msr.enable = 0; - wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); - -- return 0; -+ ret = hv_cpu_die(0); -+ return ret; - } - - static void hv_resume(void) - { - union hv_x64_msr_hypercall_contents hypercall_msr; -+ int ret; -+ -+ ret = hv_cpu_init(0); -+ WARN_ON(ret); - - /* Re-enable the hypercall page */ - rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); -@@ -288,6 +295,7 @@ static void hv_resume(void) - hv_hypercall_pg_saved = NULL; - } - -+/* Note: when the ops are called, only CPU0 is online and IRQs are disabled. */ - static struct syscore_ops hv_syscore_ops = { - .suspend = hv_suspend, - .resume = hv_resume, --- -2.26.2 - |