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Date: Wed, 24 Sep 2008 16:16:16 +0200
From: Joerg Roedel <joerg.roedel@....com>
To: Yan Li <elliot.li.tech@...il.com>
CC: linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...e.hu>,
"H. Peter Anvin" <hpa@...or.com>, rjmaomao@...il.com,
Yinghai Lu <yhlu.kernel@...il.com>,
Thomas Gleixner <tglx@...utronix.de>, nancydreaming@...il.com
Subject: Re: [PATCH 2/2] Suppress false "mtrr all empty" warning message when running as VMware guest
On Wed, Sep 24, 2008 at 08:24:37PM +0800, Yan Li wrote:
> Since the mtrr empty was detected very early before we can use DMI or
> PCI to check whether we are running as a VMware guest or not, we now
> only print an info there. Warning will only be issued later when we
> are sure that we are not running as a VMware guest.
>
> mtrr_trim_uncached_memory() is modified to return meaningful codes for
> later warning decision.
A lot of code if #ifdef'ed to vmware. Can you hide this into a header
file? This way its not very clean code I think.
> Signed-off-by: Yan Li <elliot.li.tech@...il.com>
> ---
> arch/x86/kernel/cpu/mtrr/main.c | 16 +++++++++++++++-
> arch/x86/kernel/setup.c | 27 ++++++++++++++++++++++++++-
> include/asm-x86/mtrr.h | 2 ++
> 3 files changed, 43 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/kernel/cpu/mtrr/main.c b/arch/x86/kernel/cpu/mtrr/main.c
> index b117d7f..95d1cc0 100644
> --- a/arch/x86/kernel/cpu/mtrr/main.c
> +++ b/arch/x86/kernel/cpu/mtrr/main.c
> @@ -1453,6 +1453,11 @@ static u64 __init real_trim_memory(unsigned long start_pfn,
> * all of the memory the kernel is intending to use. If not, it'll trim any
> * memory off the end by adjusting end_pfn, removing it from the kernel's
> * allocation pools, warning the user with an obnoxious message.
> + *
> + * Return code:
> + * EMTRR_ALL_BLANK (-1): not trimmed due to CPU MTRRs all blank
> + * 0: not trimmed due to other reasons
> + * 1: trimmed successfully
> */
> int __init mtrr_trim_uncached_memory(unsigned long end_pfn)
> {
> @@ -1494,11 +1499,20 @@ int __init mtrr_trim_uncached_memory(unsigned long end_pfn)
> highest_pfn = base + size;
> }
>
> - /* kvm/qemu doesn't have mtrr set right, don't trim them all */
> + /* kvm/qemu/VMware doesn't have mtrr set right, don't trim them all */
> if (!highest_pfn) {
> +#ifdef CONFIG_VMWARE_GUEST_DETECT
> + /* the "mtrr all blank" warning will be deferred until
> + * after DMI scanning and we know the machine is not a
> + * VMware guest
> + */
> + printk(KERN_INFO "CPU MTRRs all blank\n");
> + return EMTRR_ALL_BLANK;
> +#else
> WARN(!kvm_para_available(), KERN_WARNING
> "WARNING: strange, CPU MTRRs all blank?\n");
> return 0;
> +#endif
Can we move the WARN after the DMI scanning for all cases? This will
save this #ifdef and is a cleaner approach imho.
> }
>
> /* check entries number */
> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
> index 9838f25..4cbec10 100644
> --- a/arch/x86/kernel/setup.c
> +++ b/arch/x86/kernel/setup.c
> @@ -102,6 +102,7 @@
> #include <asm/percpu.h>
> #include <asm/topology.h>
> #include <asm/apicdef.h>
> +#include <asm/vmware.h>
> #ifdef CONFIG_X86_64
> #include <asm/numa_64.h>
> #endif
> @@ -593,6 +594,13 @@ struct x86_quirks *x86_quirks __initdata = &default_x86_quirks;
>
> void __init setup_arch(char **cmdline_p)
> {
> +#ifdef CONFIG_VMWARE_GUEST_DETECT
> + /* the "mtrr all blank" warning will be deferred until after
> + * DMI scanning and we know the machine is not a VMware guest
> + */
> + int cpu_mtrr_all_blank_later_warning = 0;
> +#endif
> +
> #ifdef CONFIG_X86_32
> memcpy(&boot_cpu_data, &new_cpu_data, sizeof(new_cpu_data));
> visws_early_detect();
> @@ -733,8 +741,16 @@ void __init setup_arch(char **cmdline_p)
> early_reserve_e820_mpc_new();
> /* update e820 for memory not covered by WB MTRRs */
> mtrr_bp_init();
> - if (mtrr_trim_uncached_memory(max_pfn))
> + switch (mtrr_trim_uncached_memory(max_pfn)) {
> + case 1:
> max_pfn = e820_end_of_ram_pfn();
> + break;
> +#ifdef CONFIG_VMWARE_GUEST_DETECT
> + case EMTRR_ALL_BLANK:
> + cpu_mtrr_all_blank_later_warning = 1;
> + break;
> +#endif
> + }
>
> #ifdef CONFIG_X86_32
> /* max_low_pfn get updated here */
> @@ -783,6 +799,15 @@ void __init setup_arch(char **cmdline_p)
>
> dmi_scan_machine();
>
> +#ifdef CONFIG_VMWARE_GUEST_DETECT
> + if (cpu_mtrr_all_blank_later_warning) {
> + WARN(!(kvm_para_available() || (is_vmware_guest())),
> + KERN_WARNING
> + "WARNING: strange, CPU MTRRs all blank? "
> + "Deferred from mtrr_trim_uncached_memory()\n");
> + }
> +#endif
> +
> io_delay_init();
>
> /*
> diff --git a/include/asm-x86/mtrr.h b/include/asm-x86/mtrr.h
> index a69a01a..b6d8fcb 100644
> --- a/include/asm-x86/mtrr.h
> +++ b/include/asm-x86/mtrr.h
> @@ -26,6 +26,8 @@
> #include <linux/ioctl.h>
> #include <linux/errno.h>
>
> +#define EMTRR_ALL_BLANK (-1)
> +
> #define MTRR_IOCTL_BASE 'M'
>
> struct mtrr_sentry {
> --
> 1.5.4.3
>
>
> --
> Li, Yan
>
> "Everything that is really great and inspiring is created by the
> individual who can labor in freedom."
> - Albert Einstein, in Out of My Later Years (1950)
>
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