On 30.10.2020 14:45, Andrey Ryabinin wrote:
> From: Vladimir Davydov
>
> Port diff-arch-x86-introduce-cpuid-override
>
> Recent Intel CPUs rejected CPUID masking, which is required for flex
> migration, in favor of CPUID faulting. So we need to support it in
> kenrel.
>
> This patch adds user writable file /proc/vz/cpuid_override, which
> contains CPUID override table. Each table entry must have the following
> format:
>
> op[ count]: eax ebx ecx edx
>
> where @op and optional @count define a CPUID function, whose output one
> would like to override (@op and @count are loaded to EAX and ECX
> registers respectively before calling CPUID); @eax, @ebx, @ecx, @edx -
> the desired CPUID output for the specified function. All values must be
> in HEX, 0x prefix is optional.
>
> Notes:
>
> - the file is only present on hosts that support CPUID faulting;
> - CPUID faulting is always enabled if it is supported;
> - CPUID output is overridden on all present CPUs;
> - the maximal number of entries one can override equals 16;
> - each write(2) to the file removes all existing entries before adding
>new ones, so the whole table must be written in one write(2); in
>particular writing an empty line to the file removes all existing
>rules.
>
> Example:
>
> Suppose we want to mask out SSE2 (CPUID.01H:EDX:26) and RDTSCP
> (CPUID.8001H:EDX:27). Then we should execute the following sequence:
>
> - get the current cpuid value:
>
># cpuid -r | grep -e '^\s*0x0001' -e '^\s*0x8001' | head -n 2
> 0x0001 0x00: eax=0x000306e4 ebx=0x00200800 ecx=0x7fbee3ff
> edx=0xbfebfbff
> 0x8001 0x00: eax=0x ebx=0x ecx=0x0001
> edx=0x2c100800
>
> - clear the feature bits we want to mask out and write the result to
>/proc/vz/cpuid_override:
>
># cat >/proc/vz/cpuid_override <0x0001: 0x000306e4 0x00200800 0x7fbee3ff 0xbbebfbff
>0x8001: 0x 0x 0x0001 0x24100800
>EOF
>
> - check that cpuid output was overridden:
>
># cpuid -r | grep -e '^\s*0x0001' -e '^\s*0x8001' | head -n 2
> 0x0001 0x00: eax=0x000306e4 ebx=0x00200800 ecx=0x7fbee3ff
> edx=0xbbebfbff
> 0x8001 0x00: eax=0x ebx=0x ecx=0x0001
> edx=0x24100800
>
> https://jira.sw.ru/browse/PSBM-28682
>
> Signed-off-by: Vladimir Davydov
>
> Acked-by: Cyrill Gorcunov
> =
>
> https://jira.sw.ru/browse/PSBM-33638
>
> Signed-off-by: Vladimir Davydov
> Rebase:
> Signed-off-by: Kirill Tkhai
>
> https://jira.sw.ru/browse/PSBM-121823
> [aryabinin: vz8 rebase]
> Signed-off-by: Andrey Ryabinin
For the series:
Reviewed-by: Kirill Tkhai
> ---
> arch/x86/include/asm/msr-index.h | 1 +
> arch/x86/include/asm/traps.h | 2 +
> arch/x86/kernel/Makefile | 1 +
> arch/x86/kernel/cpu/proc.c | 4 +
> arch/x86/kernel/cpuid_fault.c| 258 +++
> arch/x86/kernel/traps.c | 24 +++
> 6 files changed, 290 insertions(+)
> create mode 100644 arch/x86/kernel/cpuid_fault.c
>
> diff --git a/arch/x86/include/asm/msr-index.h
> b/arch/x86/include/asm/msr-index.h
> index 6a21c227775c..9668ec6a064d 100644
> --- a/arch/x86/include/asm/msr-index.h
> +++ b/arch/x86/include/asm/msr-index.h
> @@ -114,6 +114,7 @@
>
> #define MSR_IA32_BBL_CR_CTL 0x0119
> #define MSR_IA32_BBL_CR_CTL3 0x011e
> +#define MSR_MISC_FEATURES_ENABLES0x0140
>
> #define MSR_IA32_TSX_CTRL0x0122
> #define TSX_CTRL_RTM_DISABLE BIT(0) /* Disable RTM feature */
> diff --git a/arch/x86/include/asm/traps.h b/arch/x86/include/asm/traps.h
> index 0ae298ea01a1..0282c81719e7 100644
> --- a/arch/x86/include/asm/traps.h
> +++ b/arch/x86/include/asm/traps.h
> @@ -124,6 +124,8 @@ void __noreturn handle_stack_overflow(const char *message,
> unsigned long fault_address);
> #endif
>
> +void do_cpuid_fault(struct pt_regs *);
> +
> /* Interrupts/Exceptions */
> enum {
> X86_TRAP_DE = 0,/* 0, Divide-by-zero */
> diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
> index 431d8c6e641d..b9451b653b04 100644
> --- a/arch/x86/kernel/Makefile
> +++ b/arch/x86/kernel/Makefile
> @@ -63,6 +63,7 @@ obj-y += pci-iommu_table.o
> obj-y+= resource.o
> obj-y+= irqflags.o
> obj-y+= spec_ctrl.o
> +obj-y+= cpuid_fault.o
>
> obj-y+= process.o
> obj-y+= fpu/
> diff --git a/arch/x86/kernel/cpu/proc.c b/arch/x86/kernel/cpu/proc.c
> index 2c8522a39ed5..d6b17a60acf6 100644
> --- a/arch/x86/kernel/cpu/proc.c
> +++ b/arch/x86/kernel/cpu/proc.c
> @@ -54,6 +54,10 @@ static void show_cpuinfo_misc(struct seq_file *m, struct
> cpuinfo_x86 *c)
> }
>
