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From: Paolo Bonzini <pbonzini@redhat.com>
To: Sean Christopherson <seanjc@google.com>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Andy Lutomirski <luto@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>,
	Wanpeng Li <wanpengli@tencent.com>,
	Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
	kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
	Borislav Petkov <bp@suse.de>,
	Tom Lendacky <thomas.lendacky@amd.com>,
	Brijesh Singh <brijesh.singh@amd.com>
Subject: Re: [PATCH v2 14/14] KVM: SVM: Skip SEV cache flush if no ASIDs have been used
Date: Thu, 28 Jan 2021 16:10:24 +0100	[thread overview]
Message-ID: <55a63dfb-94a4-6ba2-31d1-c9b6830ff791@redhat.com> (raw)
In-Reply-To: <20210114003708.3798992-15-seanjc@google.com>

On 14/01/21 01:37, Sean Christopherson wrote:
> Skip SEV's expensive WBINVD and DF_FLUSH if there are no SEV ASIDs
> waiting to be reclaimed, e.g. if SEV was never used.  This "fixes" an
> issue where the DF_FLUSH fails during hardware teardown if the original
> SEV_INIT failed.  Ideally, SEV wouldn't be marked as enabled in KVM if
> SEV_INIT fails, but that's a problem for another day.
> 
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> ---
>   arch/x86/kvm/svm/sev.c | 22 ++++++++++------------
>   1 file changed, 10 insertions(+), 12 deletions(-)
> 
> diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
> index 23a4bead4a82..e71bc742d8da 100644
> --- a/arch/x86/kvm/svm/sev.c
> +++ b/arch/x86/kvm/svm/sev.c
> @@ -56,9 +56,14 @@ struct enc_region {
>   	unsigned long size;
>   };
>   
> -static int sev_flush_asids(void)
> +static int sev_flush_asids(int min_asid, int max_asid)
>   {
> -	int ret, error = 0;
> +	int ret, pos, error = 0;
> +
> +	/* Check if there are any ASIDs to reclaim before performing a flush */
> +	pos = find_next_bit(sev_reclaim_asid_bitmap, max_sev_asid, min_asid);
> +	if (pos >= max_asid)
> +		return -EBUSY;
>   
>   	/*
>   	 * DEACTIVATE will clear the WBINVD indicator causing DF_FLUSH to fail,
> @@ -80,14 +85,7 @@ static int sev_flush_asids(void)
>   /* Must be called with the sev_bitmap_lock held */
>   static bool __sev_recycle_asids(int min_asid, int max_asid)
>   {
> -	int pos;
> -
> -	/* Check if there are any ASIDs to reclaim before performing a flush */
> -	pos = find_next_bit(sev_reclaim_asid_bitmap, max_sev_asid, min_asid);
> -	if (pos >= max_asid)
> -		return false;
> -
> -	if (sev_flush_asids())
> +	if (sev_flush_asids(min_asid, max_asid))
>   		return false;
>   
>   	/* The flush process will flush all reclaimable SEV and SEV-ES ASIDs */
> @@ -1323,10 +1321,10 @@ void sev_hardware_teardown(void)
>   	if (!sev_enabled)
>   		return;
>   
> +	sev_flush_asids(0, max_sev_asid);
> +
>   	bitmap_free(sev_asid_bitmap);
>   	bitmap_free(sev_reclaim_asid_bitmap);
> -
> -	sev_flush_asids();
>   }
>   
>   int sev_cpu_init(struct svm_cpu_data *sd)
> 

I can't find 00/14 in my inbox, so: queued 1-3 and 6-14, thanks.

Paolo


  parent reply	other threads:[~2021-01-28 15:12 UTC|newest]

Thread overview: 54+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-14  0:36 [PATCH v2 00/14] KVM: SVM: Misc SEV cleanups Sean Christopherson
2021-01-14  0:36 ` [PATCH v2 01/14] KVM: SVM: Zero out the VMCB array used to track SEV ASID association Sean Christopherson
2021-01-14 15:56   ` Tom Lendacky
2021-01-14 17:13     ` Sean Christopherson
2021-01-14 20:57   ` Brijesh Singh
2021-01-14  0:36 ` [PATCH v2 02/14] KVM: SVM: Free sev_asid_bitmap during init if SEV setup fails Sean Christopherson
2021-01-14 15:49   ` Tom Lendacky
2021-01-14 17:12     ` Sean Christopherson
2021-01-14 18:02       ` Tom Lendacky
2021-01-14 19:17         ` Sean Christopherson
2021-01-14  0:36 ` [PATCH v2 03/14] KVM: SVM: Move SEV module params/variables to sev.c Sean Christopherson
2021-01-14 19:07   ` Tom Lendacky
2021-01-14 20:59   ` Brijesh Singh
2021-01-14  0:36 ` [PATCH v2 04/14] x86/cpufeatures: Assign dedicated feature word for AMD mem encryption Sean Christopherson
2021-01-14 11:35   ` Borislav Petkov
2021-01-14 17:09     ` Sean Christopherson
2021-01-14 17:16       ` Borislav Petkov
2021-01-28 15:09         ` Paolo Bonzini
2021-01-14 21:17   ` Brijesh Singh
2021-01-14  0:36 ` [PATCH v2 05/14] KVM: x86: Override reported SME/SEV feature flags with host mask Sean Christopherson
2021-01-14 21:18   ` Brijesh Singh
2021-01-28 15:07   ` Paolo Bonzini
2021-01-28 17:09     ` Sean Christopherson
2021-01-28 17:25       ` Paolo Bonzini
2021-01-14  0:37 ` [PATCH v2 06/14] x86/sev: Drop redundant and potentially misleading 'sev_enabled' Sean Christopherson
2021-01-14 17:54   ` Tom Lendacky
2021-01-14 21:24   ` Brijesh Singh
2021-01-14  0:37 ` [PATCH v2 07/14] KVM: SVM: Append "_enabled" to module-scoped SEV/SEV-ES control variables Sean Christopherson
2021-01-14 21:28   ` Brijesh Singh
2021-01-14  0:37 ` [PATCH v2 08/14] KVM: SVM: Condition sev_enabled and sev_es_enabled on CONFIG_KVM_AMD_SEV=y Sean Christopherson
2021-01-14 20:56   ` Tom Lendacky
2021-01-14 21:28   ` Brijesh Singh
2021-01-14  0:37 ` [PATCH v2 09/14] KVM: SVM: Unconditionally invoke sev_hardware_teardown() Sean Christopherson
2021-01-14 21:26   ` Tom Lendacky
2021-01-14 21:32   ` Brijesh Singh
2021-01-14  0:37 ` [PATCH v2 10/14] KVM: SVM: Explicitly check max SEV ASID during sev_hardware_setup() Sean Christopherson
2021-01-14 21:35   ` Brijesh Singh
2021-01-14 21:49   ` Tom Lendacky
2021-01-14  0:37 ` [PATCH v2 11/14] KVM: SVM: Move SEV VMCB tracking allocation to sev.c Sean Christopherson
2021-01-14 21:37   ` Brijesh Singh
2021-01-14 21:53     ` Tom Lendacky
2021-01-14 22:15   ` Tom Lendacky
2021-01-14  0:37 ` [PATCH v2 12/14] KVM: SVM: Drop redundant svm_sev_enabled() helper Sean Christopherson
2021-01-14 21:44   ` Brijesh Singh
2021-01-14 22:51   ` Tom Lendacky
2021-01-14  0:37 ` [PATCH v2 13/14] KVM: SVM: Remove an unnecessary prototype declaration of sev_flush_asids() Sean Christopherson
2021-01-14 21:45   ` Brijesh Singh
2021-01-14 22:53   ` Tom Lendacky
2021-01-14  0:37 ` [PATCH v2 14/14] KVM: SVM: Skip SEV cache flush if no ASIDs have been used Sean Christopherson
2021-01-15 15:07   ` Tom Lendacky
2021-01-15 17:19     ` Sean Christopherson
2021-01-28 15:10   ` Paolo Bonzini [this message]
2021-01-28 16:29     ` Sean Christopherson
2021-01-28 16:59       ` Paolo Bonzini

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