From 8efbc518b884e1db2dd6a6fce62d0112ab871dcf Mon Sep 17 00:00:00 2001 From: Dave Young Date: Wed, 12 Feb 2020 19:04:24 +0800 Subject: [PATCH] x86/kexec: Do not reserve EFI setup_data in the kexec e820 table The e820 table for the kexec kernel unconditionally marks setup_data as reserved because the second kernel can reuse setup_data passed by the 1st kernel's boot loader, for example SETUP_PCI marked regions like PCI BIOS, etc. SETUP_EFI types, however, are used by kexec itself to enable EFI in the 2nd kernel. Thus, it is pointless to add this type of setup_data to the kexec e820 table as reserved. IOW, what happens is this: - 1st physical boot: no SETUP_EFI. - kexec loads a new kernel and prepares a SETUP_EFI setup_data blob, then reboots the machine. - 2nd kernel sees SETUP_EFI, reserves it both in the e820 and in the kexec e820 table. - If another kexec load is executed, it prepares a new SETUP_EFI blob and then reboots the machine into the new kernel. 5. The 3rd kexec-ed kernel has two SETUP_EFI ranges reserved. And so on... Thus skip SETUP_EFI while reserving setup_data in the e820_table_kexec table because it is not needed. [ bp: Heavily massage commit message, shorten line and improve comment. ] Signed-off-by: Dave Young Signed-off-by: Borislav Petkov Link: https://lkml.kernel.org/r/20200212110424.GA2938@dhcp-128-65.nay.redhat.com --- arch/x86/kernel/e820.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c index c5399e80c59c..c92029651b85 100644 --- a/arch/x86/kernel/e820.c +++ b/arch/x86/kernel/e820.c @@ -999,7 +999,15 @@ void __init e820__reserve_setup_data(void) while (pa_data) { data = early_memremap(pa_data, sizeof(*data)); e820__range_update(pa_data, sizeof(*data)+data->len, E820_TYPE_RAM, E820_TYPE_RESERVED_KERN); - e820__range_update_kexec(pa_data, sizeof(*data)+data->len, E820_TYPE_RAM, E820_TYPE_RESERVED_KERN); + + /* + * SETUP_EFI is supplied by kexec and does not need to be + * reserved. + */ + if (data->type != SETUP_EFI) + e820__range_update_kexec(pa_data, + sizeof(*data) + data->len, + E820_TYPE_RAM, E820_TYPE_RESERVED_KERN); if (data->type == SETUP_INDIRECT && ((struct setup_indirect *)data->data)->type != SETUP_INDIRECT) {