[GIT PULL] x86 fixes

Ingo Molnar
2020-08-15T21:56:43Z

Linus,

Please pull the latest x86/urgent git tree from:

git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git x86-urgent-2020-08-15

# HEAD: a6d996cbd38b42341ad3fce74506b9fdc280e395 x86/alternatives: Acquire pte lock with interrupts enabled

Misc fixes and small updates all around the place:

- Fix mitigation state sysfs output
- Fix an FPU xstate/sxave code assumption bug triggered by Architectural LBR support
- Fix Lightning Mountain SoC TSC frequency enumeration bug
- Fix kexec debug output
- Fix kexec memory range assumption bug
- Fix a boundary condition in the crash kernel code

- Optimize porgatory.ro generation a bit
- Enable ACRN guests to use X2APIC mode
- Reduce a __text_poke() IRQs-off critical section for the benefit of PREEMPT_RT

Thanks,

Ingo

------------------>
Dilip Kota (1):
x86/tsr: Fix tsc frequency enumeration bug on Lightning Mountain SoC

Kan Liang (1):
x86/fpu/xstate: Fix an xstate size check warning with architectural LBRs

Lianbo Jiang (3):
x86/crash: Correct the address boundary of function parameters
kexec: Improve & fix crash_exclude_mem_range() to handle overlapping ranges
kexec_file: Correctly output debugging information for the PT_LOAD ELF header

Pawan Gupta (1):
x86/bugs/multihit: Fix mitigation reporting when VMX is not in use

Pingfan Liu (1):
x86/purgatory: Don't generate debug info for purgatory.ro

Sebastian Andrzej Siewior (1):
x86/alternatives: Acquire pte lock with interrupts enabled

Shuo Liu (2):
x86/acrn: Allow ACRN guest to use X2APIC mode
x86/acrn: Remove redundant chars from ACRN signature

Documentation/admin-guide/hw-vuln/multihit.rst | 4 +++
arch/x86/kernel/alternative.c | 6 ++--
arch/x86/kernel/cpu/acrn.c | 12 +++-----
arch/x86/kernel/cpu/bugs.c | 8 ++++-
arch/x86/kernel/crash.c | 2 +-
arch/x86/kernel/fpu/xstate.c | 33 ++++++++++++++++++++-
arch/x86/kernel/tsc_msr.c | 9 ++++--
arch/x86/purgatory/Makefile | 5 +++-
kernel/kexec_file.c | 41 ++++++++++++++++----------
9 files changed, 88 insertions(+), 32 deletions(-)

diff --git a/Documentation/admin-guide/hw-vuln/multihit.rst b/Documentation/admin-guide/hw-vuln/multihit.rst
index ba9988d8bce5..140e4cec38c3 100644
--- a/Documentation/admin-guide/hw-vuln/multihit.rst
+++ b/Documentation/admin-guide/hw-vuln/multihit.rst
@@ -80,6 +80,10 @@ The possible values in this file are:
- The processor is not vulnerable.
* - KVM: Mitigation: Split huge pages
- Software changes mitigate this issue.
+ * - KVM: Mitigation: VMX unsupported
+ - KVM is not vulnerable because Virtual Machine Extensions (VMX) is not supported.
+ * - KVM: Mitigation: VMX disabled
+ - KVM is not vulnerable because Virtual Machine Extensions (VMX) is disabled.
* - KVM: Vulnerable
- The processor is vulnerable, but no mitigation enabled

diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index c826cddae157..34a1b8562c31 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -874,8 +874,6 @@ static void *__text_poke(void *addr, const void *opcode, size_t len)
*/
BUG_ON(!pages[0] || (cross_page_boundary && !pages[1]));

- local_irq_save(flags);
-
/*
* Map the page without the global bit, as TLB flushing is done with
* flush_tlb_mm_range(), which is intended for non-global PTEs.
@@ -892,6 +890,8 @@ static void *__text_poke(void *addr, const void *opcode, size_t len)
*/
VM_BUG_ON(!ptep);

+ local_irq_save(flags);
+
pte = mk_pte(pages[0], pgprot);
set_pte_at(poking_mm, poking_addr, ptep, pte);

@@ -941,8 +941,8 @@ static void *__text_poke(void *addr, const void *opcode, size_t len)
*/
BUG_ON(memcmp(addr, opcode, len));

- pte_unmap_unlock(ptep, ptl);
local_irq_restore(flags);
+ pte_unmap_unlock(ptep, ptl);
return addr;
}

diff --git a/arch/x86/kernel/cpu/acrn.c b/arch/x86/kernel/cpu/acrn.c
index 1da9b1c9a2db..0b2c03943ac6 100644
--- a/arch/x86/kernel/cpu/acrn.c
+++ b/arch/x86/kernel/cpu/acrn.c
@@ -11,14 +11,15 @@

#include <linux/interrupt.h>
#include <asm/apic.h>
+#include <asm/cpufeatures.h>
#include <asm/desc.h>
#include <asm/hypervisor.h>
#include <asm/idtentry.h>
#include <asm/irq_regs.h>

-static uint32_t __init acrn_detect(void)
+static u32 __init acrn_detect(void)
{
- return hypervisor_cpuid_base("ACRNACRNACRN\0\0", 0);
+ return hypervisor_cpuid_base("ACRNACRNACRN", 0);
}

static void __init acrn_init_platform(void)
@@ -29,12 +30,7 @@ static void __init acrn_init_platform(void)

static bool acrn_x2apic_available(void)
{
- /*
- * x2apic is not supported for now. Future enablement will have to check
- * X86_FEATURE_X2APIC to determine whether x2apic is supported in the
- * guest.
- */
- return false;
+ return boot_cpu_has(X86_FEATURE_X2APIC);
}

static void (*acrn_intr_handler)(void);
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index f0b743a2fe9c..d3f0db463f96 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -31,6 +31,7 @@
#include <asm/intel-family.h>
#include <asm/e820/api.h>
#include <asm/hypervisor.h>
+#include <asm/tlbflush.h>

#include "cpu.h"

@@ -1549,7 +1550,12 @@ static ssize_t l1tf_show_state(char *buf)

static ssize_t itlb_multihit_show_state(char *buf)
{
- if (itlb_multihit_kvm_mitigation)
+ if (!boot_cpu_has(X86_FEATURE_MSR_IA32_FEAT_CTL) ||
+ !boot_cpu_has(X86_FEATURE_VMX))
+ return sprintf(buf, "KVM: Mitigation: VMX unsupported\n");
+ else if (!(cr4_read_shadow() & X86_CR4_VMXE))
+ return sprintf(buf, "KVM: Mitigation: VMX disabled\n");
+ else if (itlb_multihit_kvm_mitigation)
return sprintf(buf, "KVM: Mitigation: Split huge pages\n");
else
return sprintf(buf, "KVM: Vulnerable\n");
diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c
index fd87b59452a3..a8f3af257e26 100644
--- a/arch/x86/kernel/crash.c
+++ b/arch/x86/kernel/crash.c
@@ -230,7 +230,7 @@ static int elf_header_exclude_ranges(struct crash_mem *cmem)
int ret = 0;

/* Exclude the low 1M because it is always reserved */
- ret = crash_exclude_mem_range(cmem, 0, 1<<20);
+ ret = crash_exclude_mem_range(cmem, 0, (1<<20)-1);
if (ret)
return ret;

diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index be2a68a09d19..6073e342a1ed 100644
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -611,6 +611,10 @@ static void check_xstate_against_struct(int nr)
* This essentially double-checks what the cpu told us about
* how large the XSAVE buffer needs to be. We are recalculating
* it to be safe.
+ *
+ * Dynamic XSAVE features allocate their own buffers and are not
+ * covered by these checks. Only the size of the buffer for task->fpu
+ * is checked here.
*/
static void do_extra_xstate_size_checks(void)
{
@@ -673,6 +677,33 @@ static unsigned int __init get_xsaves_size(void)
return ebx;
}

+/*
+ * Get the total size of the enabled xstates without the dynamic supervisor
+ * features.
+ */
+static unsigned int __init get_xsaves_size_no_dynamic(void)
+{
+ u64 mask = xfeatures_mask_dynamic();
+ unsigned int size;
+
+ if (!mask)
+ return get_xsaves_size();
+
+ /* Disable dynamic features. */
+ wrmsrl(MSR_IA32_XSS, xfeatures_mask_supervisor());
+
+ /*
+ * Ask the hardware what size is required of the buffer.
+ * This is the size required for the task->fpu buffer.
+ */
+ size = get_xsaves_size();
+
+ /* Re-enable dynamic features so XSAVES will work on them again. */
+ wrmsrl(MSR_IA32_XSS, xfeatures_mask_supervisor() | mask);
+
+ return size;
+}
+
static unsigned int __init get_xsave_size(void)
{
unsigned int eax, ebx, ecx, edx;
@@ -710,7 +741,7 @@ static int __init init_xstate_size(void)
xsave_size = get_xsave_size();

if (boot_cpu_has(X86_FEATURE_XSAVES))
- possible_xstate_size = get_xsaves_size();
+ possible_xstate_size = get_xsaves_size_no_dynamic();
else
possible_xstate_size = xsave_size;

diff --git a/arch/x86/kernel/tsc_msr.c b/arch/x86/kernel/tsc_msr.c
index 4fec6f3a1858..a654a9b4b77c 100644
--- a/arch/x86/kernel/tsc_msr.c
+++ b/arch/x86/kernel/tsc_msr.c
@@ -133,10 +133,15 @@ static const struct freq_desc freq_desc_ann = {
.mask = 0x0f,
};

-/* 24 MHz crystal? : 24 * 13 / 4 = 78 MHz */
+/*
+ * 24 MHz crystal? : 24 * 13 / 4 = 78 MHz
+ * Frequency step for Lightning Mountain SoC is fixed to 78 MHz,
+ * so all the frequency entries are 78000.
+ */
static const struct freq_desc freq_desc_lgm = {
.use_msr_plat = true,
- .freqs = { 78000, 78000, 78000, 78000, 78000, 78000, 78000, 78000 },
+ .freqs = { 78000, 78000, 78000, 78000, 78000, 78000, 78000, 78000,
+ 78000, 78000, 78000, 78000, 78000, 78000, 78000, 78000 },
.mask = 0x0f,
};

diff --git a/arch/x86/purgatory/Makefile b/arch/x86/purgatory/Makefile
index 088bd764e0b7..d24b43a4451a 100644
--- a/arch/x86/purgatory/Makefile
+++ b/arch/x86/purgatory/Makefile
@@ -32,7 +32,7 @@ KCOV_INSTRUMENT := n
# make up the standalone purgatory.ro

PURGATORY_CFLAGS_REMOVE := -mcmodel=kernel
-PURGATORY_CFLAGS := -mcmodel=large -ffreestanding -fno-zero-initialized-in-bss
+PURGATORY_CFLAGS := -mcmodel=large -ffreestanding -fno-zero-initialized-in-bss -g0
PURGATORY_CFLAGS += $(DISABLE_STACKLEAK_PLUGIN) -DDISABLE_BRANCH_PROFILING
PURGATORY_CFLAGS += $(call cc-option,-fno-stack-protector)

@@ -64,6 +64,9 @@ CFLAGS_sha256.o += $(PURGATORY_CFLAGS)
CFLAGS_REMOVE_string.o += $(PURGATORY_CFLAGS_REMOVE)
CFLAGS_string.o += $(PURGATORY_CFLAGS)

+AFLAGS_REMOVE_setup-x86_$(BITS).o += -Wa,-gdwarf-2
+AFLAGS_REMOVE_entry64.o += -Wa,-gdwarf-2
+
$(obj)/purgatory.ro: $(PURGATORY_OBJS) FORCE
$(call if_changed,ld)

diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
index 94661d2d13ad..3f7867c1820f 100644
--- a/kernel/kexec_file.c
+++ b/kernel/kexec_file.c
@@ -1157,24 +1157,26 @@ int crash_exclude_mem_range(struct crash_mem *mem,
unsigned long long mstart, unsigned long long mend)
{
int i, j;
- unsigned long long start, end;
+ unsigned long long start, end, p_start, p_end;
struct crash_mem_range temp_range = {0, 0};

for (i = 0; i < mem->nr_ranges; i++) {
start = mem->ranges[i].start;
end = mem->ranges[i].end;
+ p_start = mstart;
+ p_end = mend;

if (mstart > end || mend < start)
continue;

/* Truncate any area outside of range */
if (mstart < start)
- mstart = start;
+ p_start = start;
if (mend > end)
- mend = end;
+ p_end = end;

/* Found completely overlapping range */
- if (mstart == start && mend == end) {
+ if (p_start == start && p_end == end) {
mem->ranges[i].start = 0;
mem->ranges[i].end = 0;
if (i < mem->nr_ranges - 1) {
@@ -1185,20 +1187,29 @@ int crash_exclude_mem_range(struct crash_mem *mem,
mem->ranges[j].end =
mem->ranges[j+1].end;
}
+
+ /*
+ * Continue to check if there are another overlapping ranges
+ * from the current position because of shifting the above
+ * mem ranges.
+ */
+ i--;
+ mem->nr_ranges--;
+ continue;
}
mem->nr_ranges--;
return 0;
}

- if (mstart > start && mend < end) {
+ if (p_start > start && p_end < end) {
/* Split original range */
- mem->ranges[i].end = mstart - 1;
- temp_range.start = mend + 1;
+ mem->ranges[i].end = p_start - 1;
+ temp_range.start = p_end + 1;
temp_range.end = end;
- } else if (mstart != start)
- mem->ranges[i].end = mstart - 1;
+ } else if (p_start != start)
+ mem->ranges[i].end = p_start - 1;
else
- mem->ranges[i].start = mend + 1;
+ mem->ranges[i].start = p_end + 1;
break;
}

@@ -1235,7 +1246,7 @@ int crash_prepare_elf64_headers(struct crash_mem *mem, int kernel_map,
unsigned long long notes_addr;
unsigned long mstart, mend;

- /* extra phdr for vmcoreinfo elf note */
+ /* extra phdr for vmcoreinfo ELF note */
nr_phdr = nr_cpus + 1;
nr_phdr += mem->nr_ranges;

@@ -1243,7 +1254,7 @@ int crash_prepare_elf64_headers(struct crash_mem *mem, int kernel_map,
* kexec-tools creates an extra PT_LOAD phdr for kernel text mapping
* area (for example, ffffffff80000000 - ffffffffa0000000 on x86_64).
* I think this is required by tools like gdb. So same physical
- * memory will be mapped in two elf headers. One will contain kernel
+ * memory will be mapped in two ELF headers. One will contain kernel
* text virtual addresses and other will have __va(physical) addresses.
*/

@@ -1270,7 +1281,7 @@ int crash_prepare_elf64_headers(struct crash_mem *mem, int kernel_map,
ehdr->e_ehsize = sizeof(Elf64_Ehdr);
ehdr->e_phentsize = sizeof(Elf64_Phdr);

- /* Prepare one phdr of type PT_NOTE for each present cpu */
+ /* Prepare one phdr of type PT_NOTE for each present CPU */
for_each_present_cpu(cpu) {
phdr->p_type = PT_NOTE;
notes_addr = per_cpu_ptr_to_phys(per_cpu_ptr(crash_notes, cpu));
@@ -1312,10 +1323,10 @@ int crash_prepare_elf64_headers(struct crash_mem *mem, int kernel_map,
phdr->p_filesz = phdr->p_memsz = mend - mstart + 1;
phdr->p_align = 0;
ehdr->e_phnum++;
- phdr++;
- pr_debug("Crash PT_LOAD elf header. phdr=%p vaddr=0x%llx, paddr=0x%llx, sz=0x%llx e_phnum=%d p_offset=0x%llx\n",
+ pr_debug("Crash PT_LOAD ELF header. phdr=%p vaddr=0x%llx, paddr=0x%llx, sz=0x%llx e_phnum=%d p_offset=0x%llx\n",
phdr, phdr->p_vaddr, phdr->p_paddr, phdr->p_filesz,
ehdr->e_phnum, phdr->p_offset);
+ phdr++;
}

*addr = buf;