2022-04-22 19:49:14

by Srinivas Pandruvada

Subject: [PATCH] platform/x86: intel-uncore-freq: Prevent driver loading in guests

Loading this driver in guests results in unchecked MSR access error for
MSR 0x620.

There is no use of reading and modifying package/die scoped uncore MSRs
in guests. So check for CPU feature X86_FEATURE_HYPERVISOR to prevent
loading of this driver in guests.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=215870
Suggested-by: Borislav Petkov <[email protected]>
Signed-off-by: Srinivas Pandruvada <[email protected]>
---
drivers/platform/x86/intel/uncore-frequency/uncore-frequency.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/drivers/platform/x86/intel/uncore-frequency/uncore-frequency.c b/drivers/platform/x86/intel/uncore-frequency/uncore-frequency.c
index c61f804dd44e..8f9c571d7257 100644
--- a/drivers/platform/x86/intel/uncore-frequency/uncore-frequency.c
+++ b/drivers/platform/x86/intel/uncore-frequency/uncore-frequency.c
@@ -212,6 +212,9 @@ static int __init intel_uncore_init(void)
const struct x86_cpu_id *id;
int ret;

+ if (cpu_feature_enabled(X86_FEATURE_HYPERVISOR))
+ return -ENODEV;
+
id = x86_match_cpu(intel_uncore_cpu_ids);
if (!id)
return -ENODEV;
--
2.31.1

2022-04-27 15:14:56

by Hans de Goede

Subject: Re: [PATCH] platform/x86: intel-uncore-freq: Prevent driver loading in guests

Hi,

On 4/21/22 20:41, Srinivas Pandruvada wrote:
> Loading this driver in guests results in unchecked MSR access error for
> MSR 0x620.
>
> There is no use of reading and modifying package/die scoped uncore MSRs
> in guests. So check for CPU feature X86_FEATURE_HYPERVISOR to prevent
> loading of this driver in guests.
>
> Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=215870
> Suggested-by: Borislav Petkov <[email protected]>
> Signed-off-by: Srinivas Pandruvada <[email protected]>

Thank you for your patch, I've applied this patch to my review-hans
branch:
https://git.kernel.org/pub/scm/linux/kernel/git/pdx86/platform-drivers-x86.git/log/?h=review-hans

Note it will show up in my review-hans branch once I've pushed my
local branch there, which might take a while.

Once I've run some tests on this branch the patches there will be
added to the platform-drivers-x86/for-next branch and eventually
will be included in the pdx86 pull-request to Linus for the next
merge-window.

Regards,

Hans



> ---
> drivers/platform/x86/intel/uncore-frequency/uncore-frequency.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/drivers/platform/x86/intel/uncore-frequency/uncore-frequency.c b/drivers/platform/x86/intel/uncore-frequency/uncore-frequency.c
> index c61f804dd44e..8f9c571d7257 100644
> --- a/drivers/platform/x86/intel/uncore-frequency/uncore-frequency.c
> +++ b/drivers/platform/x86/intel/uncore-frequency/uncore-frequency.c
> @@ -212,6 +212,9 @@ static int __init intel_uncore_init(void)
> const struct x86_cpu_id *id;
> int ret;
>
> + if (cpu_feature_enabled(X86_FEATURE_HYPERVISOR))
> + return -ENODEV;
> +
> id = x86_match_cpu(intel_uncore_cpu_ids);
> if (!id)
> return -ENODEV;