From: Paolo Bonzini <pbonzini@redhat.com>
To: Brijesh Singh <brijesh.singh@amd.com>,
x86@kernel.org, linux-kernel@vger.kernel.org,
kvm@vger.kernel.org
Cc: "Tom Lendacky" <thomas.lendacky@amd.com>,
"Thomas Gleixner" <tglx@linutronix.de>,
"Borislav Petkov" <bp@suse.de>, "H. Peter Anvin" <hpa@zytor.com>,
"Sean Christopherson" <sean.j.christopherson@intel.com>,
"Radim Krčmář" <rkrcmar@redhat.com>
Subject: Re: [PATCH v6 4/5] x86/kvm: use __decrypted attribute in shared variables
Date: Mon, 10 Sep 2018 14:29:07 +0200 [thread overview]
Message-ID: <fd60e2d5-3d01-0b21-1589-a6cb26e7e6a6@redhat.com> (raw)
In-Reply-To: <1536343050-18532-5-git-send-email-brijesh.singh@amd.com>
On 07/09/2018 19:57, Brijesh Singh wrote:
> Commit: 368a540e0232 (x86/kvmclock: Remove memblock dependency)
> caused SEV guest regression. When SEV is active, we map the shared
> variables (wall_clock and hv_clock_boot) with C=0 to ensure that both
> the guest and the hypervisor are able to access the data. To map the
> variables we use kernel_physical_mapping_init() to split the large pages,
> but splitting large pages requires allocating a new PMD, which fails now
> that kvmclock initialization is called early during boot.
>
> Recently we added a special .data..decrypted section to hold the shared
> variables. This section is mapped with C=0 early during boot. Use
> __decrypted attribute to put the wall_clock and hv_clock_boot in
> .data..decrypted section so that they are mapped with C=0.
>
> Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
> Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
> Fixes: 368a540e0232 ("x86/kvmclock: Remove memblock dependency")
> Cc: Tom Lendacky <thomas.lendacky@amd.com>
> Cc: kvm@vger.kernel.org
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Borislav Petkov <bp@suse.de>
> Cc: "H. Peter Anvin" <hpa@zytor.com>
> Cc: linux-kernel@vger.kernel.org
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Cc: Sean Christopherson <sean.j.christopherson@intel.com>
> Cc: kvm@vger.kernel.org
> Cc: "Radim Krčmář" <rkrcmar@redhat.com>
> ---
> arch/x86/kernel/kvmclock.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c
> index 1e67646..376fd3a 100644
> --- a/arch/x86/kernel/kvmclock.c
> +++ b/arch/x86/kernel/kvmclock.c
> @@ -61,8 +61,8 @@ early_param("no-kvmclock-vsyscall", parse_no_kvmclock_vsyscall);
> (PAGE_SIZE / sizeof(struct pvclock_vsyscall_time_info))
>
> static struct pvclock_vsyscall_time_info
> - hv_clock_boot[HVC_BOOT_ARRAY_SIZE] __aligned(PAGE_SIZE);
> -static struct pvclock_wall_clock wall_clock;
> + hv_clock_boot[HVC_BOOT_ARRAY_SIZE] __decrypted __aligned(PAGE_SIZE);
> +static struct pvclock_wall_clock wall_clock __decrypted;
> static DEFINE_PER_CPU(struct pvclock_vsyscall_time_info *, hv_clock_per_cpu);
>
> static inline struct pvclock_vcpu_time_info *this_cpu_pvti(void)
>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
(Though perhaps __noencrypt or __unencrypted would be a bit more
accurate; likewise for the freeing function added in patch 5).
Paolo
next prev parent reply other threads:[~2018-09-10 12:29 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-07 17:57 [PATCH v6 0/5] x86: Fix SEV guest regression Brijesh Singh
2018-09-07 17:57 ` [PATCH v6 1/5] x86/mm: Restructure sme_encrypt_kernel() Brijesh Singh
2018-09-10 11:32 ` Borislav Petkov
2018-09-07 17:57 ` [PATCH v6 2/5] x86/mm: fix sme_populate_pgd() to update page flags Brijesh Singh
2018-09-10 11:36 ` Borislav Petkov
2018-09-10 12:28 ` Brijesh Singh
2018-09-10 12:32 ` Borislav Petkov
2018-09-07 17:57 ` [PATCH v6 3/5] x86/mm: add .data..decrypted section to hold shared variables Brijesh Singh
2018-09-10 11:54 ` Borislav Petkov
2018-09-10 12:33 ` Brijesh Singh
2018-09-07 17:57 ` [PATCH v6 4/5] x86/kvm: use __decrypted attribute in " Brijesh Singh
2018-09-10 12:04 ` Borislav Petkov
2018-09-10 13:15 ` Sean Christopherson
2018-09-10 13:29 ` Thomas Gleixner
2018-09-10 15:34 ` Borislav Petkov
2018-09-10 12:29 ` Paolo Bonzini [this message]
2018-09-10 12:33 ` Borislav Petkov
2018-09-10 12:46 ` Paolo Bonzini
2018-09-07 17:57 ` [PATCH v6 5/5] x86/kvm: Avoid dynamic allocation of pvclock data when SEV is active Brijesh Singh
2018-09-10 12:27 ` Borislav Petkov
2018-09-10 13:15 ` Brijesh Singh
2018-09-10 13:29 ` Sean Christopherson
2018-09-10 15:10 ` Brijesh Singh
2018-09-10 15:28 ` Sean Christopherson
2018-09-10 15:30 ` Brijesh Singh
2018-09-10 16:48 ` Borislav Petkov
2018-09-11 9:26 ` Paolo Bonzini
2018-09-11 10:01 ` Borislav Petkov
2018-09-11 10:19 ` Paolo Bonzini
2018-09-11 10:25 ` Borislav Petkov
2018-09-11 11:07 ` Paolo Bonzini
2018-09-11 13:55 ` Borislav Petkov
2018-09-11 14:00 ` Paolo Bonzini
2018-09-10 15:53 ` Borislav Petkov
2018-09-10 16:13 ` Sean Christopherson
2018-09-10 16:14 ` Brijesh Singh
2018-09-10 12:28 ` Paolo Bonzini
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