x86/tsc: Try to wrangle PV clocks vs. TSC

[PATCH 04/16] x86/sev: Mark TSC as reliable when configuring Secure TSC

Posted by Sean Christopherson 1 month, 1 week ago

Move the code to mark the TSC as reliable from sme_early_init() to
snp_secure_tsc_init().  The only reader of TSC_RELIABLE is the aptly
named check_system_tsc_reliable(), which runs in tsc_init(), i.e.
after snp_secure_tsc_init().

This will allow consolidating the handling of TSC_KNOWN_FREQ and
TSC_RELIABLE when overriding the TSC calibration routine.

Cc: Nikunj A Dadhania <nikunj@amd.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/x86/coco/sev/core.c      | 2 ++
 arch/x86/mm/mem_encrypt_amd.c | 3 ---
 2 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/arch/x86/coco/sev/core.c b/arch/x86/coco/sev/core.c
index 684cef70edc1..e6ce4ca72465 100644
--- a/arch/x86/coco/sev/core.c
+++ b/arch/x86/coco/sev/core.c
@@ -3288,6 +3288,8 @@ void __init snp_secure_tsc_init(void)
 		return;
 
 	setup_force_cpu_cap(X86_FEATURE_TSC_KNOWN_FREQ);
+	setup_force_cpu_cap(X86_FEATURE_TSC_RELIABLE);
+
 	rdmsrl(MSR_AMD64_GUEST_TSC_FREQ, tsc_freq_mhz);
 	snp_tsc_freq_khz = (unsigned long)(tsc_freq_mhz * 1000);
 
diff --git a/arch/x86/mm/mem_encrypt_amd.c b/arch/x86/mm/mem_encrypt_amd.c
index b56c5c073003..774f9677458f 100644
--- a/arch/x86/mm/mem_encrypt_amd.c
+++ b/arch/x86/mm/mem_encrypt_amd.c
@@ -541,9 +541,6 @@ void __init sme_early_init(void)
 	 * kernel mapped.
 	 */
 	snp_update_svsm_ca();
-
-	if (sev_status & MSR_AMD64_SNP_SECURE_TSC)
-		setup_force_cpu_cap(X86_FEATURE_TSC_RELIABLE);
 }
 
 void __init mem_encrypt_free_decrypted_mem(void)
-- 
2.48.1.362.g079036d154-goog

Re: [PATCH 04/16] x86/sev: Mark TSC as reliable when configuring Secure TSC

Posted by Nikunj A Dadhania 1 month, 1 week ago

Sean Christopherson <seanjc@google.com> writes:

> Move the code to mark the TSC as reliable from sme_early_init() to
> snp_secure_tsc_init().  The only reader of TSC_RELIABLE is the aptly
> named check_system_tsc_reliable(), which runs in tsc_init(), i.e.
> after snp_secure_tsc_init().
>
> This will allow consolidating the handling of TSC_KNOWN_FREQ and
> TSC_RELIABLE when overriding the TSC calibration routine.
>
> Cc: Nikunj A Dadhania <nikunj@amd.com>
> Cc: Tom Lendacky <thomas.lendacky@amd.com>
> Signed-off-by: Sean Christopherson <seanjc@google.com>

Reviewed-by: Nikunj A Dadhania <nikunj@amd.com>

> ---
>  arch/x86/coco/sev/core.c      | 2 ++
>  arch/x86/mm/mem_encrypt_amd.c | 3 ---
>  2 files changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/arch/x86/coco/sev/core.c b/arch/x86/coco/sev/core.c
> index 684cef70edc1..e6ce4ca72465 100644
> --- a/arch/x86/coco/sev/core.c
> +++ b/arch/x86/coco/sev/core.c
> @@ -3288,6 +3288,8 @@ void __init snp_secure_tsc_init(void)
>  		return;
>  
>  	setup_force_cpu_cap(X86_FEATURE_TSC_KNOWN_FREQ);
> +	setup_force_cpu_cap(X86_FEATURE_TSC_RELIABLE);
> +
>  	rdmsrl(MSR_AMD64_GUEST_TSC_FREQ, tsc_freq_mhz);
>  	snp_tsc_freq_khz = (unsigned long)(tsc_freq_mhz * 1000);
>  
> diff --git a/arch/x86/mm/mem_encrypt_amd.c b/arch/x86/mm/mem_encrypt_amd.c
> index b56c5c073003..774f9677458f 100644
> --- a/arch/x86/mm/mem_encrypt_amd.c
> +++ b/arch/x86/mm/mem_encrypt_amd.c
> @@ -541,9 +541,6 @@ void __init sme_early_init(void)
>  	 * kernel mapped.
>  	 */
>  	snp_update_svsm_ca();
> -
> -	if (sev_status & MSR_AMD64_SNP_SECURE_TSC)
> -		setup_force_cpu_cap(X86_FEATURE_TSC_RELIABLE);
>  }
>  
>  void __init mem_encrypt_free_decrypted_mem(void)
> -- 
> 2.48.1.362.g079036d154-goog