linux-kernel - [RFC PATCH v2 5/7] iommu/amd: Don't fail snp

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20230213103402.1189285-6-jpiotrowski@linux.microsoft.com>
Date:   Mon, 13 Feb 2023 10:34:00 +0000
From:   Jeremi Piotrowski <jpiotrowski@...ux.microsoft.com>
To:     linux-kernel@...r.kernel.org
Cc:     Jeremi Piotrowski <jpiotrowski@...ux.microsoft.com>,
        Wei Liu <wei.liu@...nel.org>, Dexuan Cui <decui@...rosoft.com>,
        Tianyu Lan <Tianyu.Lan@...rosoft.com>,
        Michael Kelley <mikelley@...rosoft.com>,
        linux-hyperv@...r.kernel.org,
        Brijesh Singh <brijesh.singh@....com>,
        Michael Roth <michael.roth@....com>,
        Ashish Kalra <ashish.kalra@....com>,
        Tom Lendacky <thomas.lendacky@....com>,
        Joerg Roedel <joro@...tes.org>,
        Suravee Suthikulpanit <suravee.suthikulpanit@....com>,
        iommu@...ts.linux.dev
Subject: [RFC PATCH v2 5/7] iommu/amd: Don't fail snp_enable when running virtualized

Hyper-V VMs do not have access to an IOMMU but can support hosting SNP
VMs. amd_iommu_snp_enable() is on the SNP init path and should not fail
in that case.

Signed-off-by: Jeremi Piotrowski <jpiotrowski@...ux.microsoft.com>
---
 drivers/iommu/amd/init.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c
index d1270e3c5baf..8049dbe78a27 100644
--- a/drivers/iommu/amd/init.c
+++ b/drivers/iommu/amd/init.c
@@ -3619,6 +3619,12 @@ int amd_iommu_pc_set_reg(struct amd_iommu *iommu, u8 bank, u8 cntr, u8 fxn, u64
 #ifdef CONFIG_AMD_MEM_ENCRYPT
 int amd_iommu_snp_enable(void)
 {
+	/*
+	 * If we're running virtualized there doesn't have to be an IOMMU for SNP to work.
+	 */
+	if (init_state == IOMMU_NOT_FOUND && boot_cpu_has(X86_FEATURE_HYPERVISOR))
+		return 0;
+
 	/*
 	 * The SNP support requires that IOMMU must be enabled, and is
 	 * not configured in the passthrough mode.
-- 
2.25.1