This is needed for hibernation, e.g. when we resume the old kernel, we need to disable the "current" kernel's hypercall page and then resume the old kernel's. Signed-off-by: Dexuan Cui <decui@xxxxxxxxxxxxx> Reviewed-by: Michael Kelley <mikelley@xxxxxxxxxxxxx> --- This patch is part of the v5 patchset: https://lkml.org/lkml/2019/9/5/1158 https://lkml.org/lkml/2019/9/5/1159 The change is: I set 'hv_hypercall_pg' to NULL in hv_suspend(), and restore it in hv_resume(). This is suggested by Vitaly Kuznetsov. There is no other change, compared to v1 (v2~v5 were posted with the other patches). Please pick up this patch onto the tip.git tree's branch x86/hyperv. arch/x86/hyperv/hv_init.c | 48 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 48 insertions(+) diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c index 426dc8b78193..c170653da589 100644 --- a/arch/x86/hyperv/hv_init.c +++ b/arch/x86/hyperv/hv_init.c @@ -20,11 +20,15 @@ #include <linux/hyperv.h> #include <linux/slab.h> #include <linux/cpuhotplug.h> +#include <linux/syscore_ops.h> #include <clocksource/hyperv_timer.h> void *hv_hypercall_pg; EXPORT_SYMBOL_GPL(hv_hypercall_pg); +/* Save the hypercall page temporarily for hibernation */ +static void *hv_hypercall_pg_saved; + u32 *hv_vp_index; EXPORT_SYMBOL_GPL(hv_vp_index); @@ -245,6 +249,46 @@ static int __init hv_pci_init(void) return 1; } +static int hv_suspend(void) +{ + union hv_x64_msr_hypercall_contents hypercall_msr; + + /* + * Reset hypercall page reference before reset the page, + * let hypercall operations fail safely rather than + * panic the kernel for using invalid hypercall page + */ + hv_hypercall_pg_saved = hv_hypercall_pg; + hv_hypercall_pg = NULL; + + /* Reset the hypercall page */ + rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); + hypercall_msr.enable = 0; + wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); + + return 0; +} + +static void hv_resume(void) +{ + union hv_x64_msr_hypercall_contents hypercall_msr; + + /* Re-enable the hypercall page */ + rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); + hypercall_msr.enable = 1; + hypercall_msr.guest_physical_address = + vmalloc_to_pfn(hv_hypercall_pg_saved); + wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); + + hv_hypercall_pg = hv_hypercall_pg_saved; + hv_hypercall_pg_saved = NULL; +} + +static struct syscore_ops hv_syscore_ops = { + .suspend = hv_suspend, + .resume = hv_resume, +}; + /* * This function is to be invoked early in the boot sequence after the * hypervisor has been detected. @@ -329,6 +373,8 @@ void __init hyperv_init(void) x86_init.pci.arch_init = hv_pci_init; + register_syscore_ops(&hv_syscore_ops); + return; remove_cpuhp_state: @@ -348,6 +394,8 @@ void hyperv_cleanup(void) { union hv_x64_msr_hypercall_contents hypercall_msr; + unregister_syscore_ops(&hv_syscore_ops); + /* Reset our OS id */ wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0); -- 2.19.1
