From 80f73c9f7468b15484e3ee4a29870fc9fa0419cc Mon Sep 17 00:00:00 2001 From: Wei Liu Date: Wed, 3 Feb 2021 15:04:26 +0000 Subject: [PATCH] x86/hyperv: handling hypercall page setup for root When Linux is running as the root partition, the hypercall page will have already been setup by Hyper-V. Copy the content over to the allocated page. Add checks to hv_suspend & co to bail early because they are not supported in this setup yet. Signed-off-by: Lillian Grassin-Drake Signed-off-by: Sunil Muthuswamy Signed-off-by: Nuno Das Neves Co-Developed-by: Lillian Grassin-Drake Co-Developed-by: Sunil Muthuswamy Co-Developed-by: Nuno Das Neves Signed-off-by: Wei Liu Reviewed-by: Michael Kelley Link: https://lore.kernel.org/r/20210203150435.27941-8-wei.liu@kernel.org --- arch/x86/hyperv/hv_init.c | 37 ++++++++++++++++++++++++++++++++++--- 1 file changed, 34 insertions(+), 3 deletions(-) diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c index 612c555fb9aa7..aeea8fbf3c237 100644 --- a/arch/x86/hyperv/hv_init.c +++ b/arch/x86/hyperv/hv_init.c @@ -27,6 +27,7 @@ #include #include #include +#include int hyperv_init_cpuhp; u64 hv_current_partition_id = ~0ull; @@ -286,6 +287,9 @@ static int hv_suspend(void) union hv_x64_msr_hypercall_contents hypercall_msr; int ret; + if (hv_root_partition) + return -EPERM; + /* * Reset the hypercall page as it is going to be invalidated * accross hibernation. Setting hv_hypercall_pg to NULL ensures @@ -454,8 +458,35 @@ void __init hyperv_init(void) rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); hypercall_msr.enable = 1; - hypercall_msr.guest_physical_address = vmalloc_to_pfn(hv_hypercall_pg); - wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); + + if (hv_root_partition) { + struct page *pg; + void *src, *dst; + + /* + * For the root partition, the hypervisor will set up its + * hypercall page. The hypervisor guarantees it will not show + * up in the root's address space. The root can't change the + * location of the hypercall page. + * + * Order is important here. We must enable the hypercall page + * so it is populated with code, then copy the code to an + * executable page. + */ + wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); + + pg = vmalloc_to_page(hv_hypercall_pg); + dst = kmap(pg); + src = memremap(hypercall_msr.guest_physical_address << PAGE_SHIFT, PAGE_SIZE, + MEMREMAP_WB); + BUG_ON(!(src && dst)); + memcpy(dst, src, HV_HYP_PAGE_SIZE); + memunmap(src); + kunmap(pg); + } else { + hypercall_msr.guest_physical_address = vmalloc_to_pfn(hv_hypercall_pg); + wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); + } /* * hyperv_init() is called before LAPIC is initialized: see @@ -604,7 +635,7 @@ EXPORT_SYMBOL_GPL(hv_is_hyperv_initialized); bool hv_is_hibernation_supported(void) { - return acpi_sleep_state_supported(ACPI_STATE_S4); + return !hv_root_partition && acpi_sleep_state_supported(ACPI_STATE_S4); } EXPORT_SYMBOL_GPL(hv_is_hibernation_supported);