linux-kernel - [PATCH Part2 RFC v4 19/40] crypto: ccp: provide APIs to query extended attestation report

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Date:   Wed,  7 Jul 2021 13:35:55 -0500
From:   Brijesh Singh <brijesh.singh@....com>
To:     x86@...nel.org, linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        linux-efi@...r.kernel.org, platform-driver-x86@...r.kernel.org,
        linux-coco@...ts.linux.dev, linux-mm@...ck.org,
        linux-crypto@...r.kernel.org
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Joerg Roedel <jroedel@...e.de>,
        Tom Lendacky <thomas.lendacky@....com>,
        "H. Peter Anvin" <hpa@...or.com>, Ard Biesheuvel <ardb@...nel.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Andy Lutomirski <luto@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Sergio Lopez <slp@...hat.com>, Peter Gonda <pgonda@...gle.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
        David Rientjes <rientjes@...gle.com>,
        Dov Murik <dovmurik@...ux.ibm.com>,
        Tobin Feldman-Fitzthum <tobin@....com>,
        Borislav Petkov <bp@...en8.de>,
        Michael Roth <michael.roth@....com>,
        Vlastimil Babka <vbabka@...e.cz>, tony.luck@...el.com,
        npmccallum@...hat.com, brijesh.ksingh@...il.com,
        Brijesh Singh <brijesh.singh@....com>
Subject: [PATCH Part2 RFC v4 19/40] crypto: ccp: provide APIs to query extended attestation report

Version 2 of the GHCB specification defines VMGEXIT that is used to get
the extended attestation report. The extended attestation report includes
the certificate blobs provided through the SNP_SET_EXT_CONFIG.

The snp_guest_ext_guest_request() will be used by the hypervisor to get
the extended attestation report. See the GHCB specification for more
details.

Signed-off-by: Brijesh Singh <brijesh.singh@....com>
---
 drivers/crypto/ccp/sev-dev.c | 43 ++++++++++++++++++++++++++++++++++++
 include/linux/psp-sev.h      | 24 ++++++++++++++++++++
 2 files changed, 67 insertions(+)

diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
index 1984a7b2c4e1..4cc9c1dff49f 100644
--- a/drivers/crypto/ccp/sev-dev.c
+++ b/drivers/crypto/ccp/sev-dev.c
@@ -22,6 +22,7 @@
 #include <linux/firmware.h>
 #include <linux/gfp.h>
 #include <linux/cpufeature.h>
+#include <linux/sev-guest.h>
 
 #include <asm/smp.h>
 
@@ -1616,6 +1617,48 @@ int snp_guest_dbg_decrypt(struct sev_data_snp_dbg *data, int *error)
 }
 EXPORT_SYMBOL_GPL(snp_guest_dbg_decrypt);
 
+int snp_guest_ext_guest_request(struct sev_data_snp_guest_request *data,
+				unsigned long vaddr, unsigned long *npages, unsigned long *fw_err)
+{
+	unsigned long expected_npages;
+	struct sev_device *sev;
+	int rc;
+
+	if (!psp_master || !psp_master->sev_data)
+		return -ENODEV;
+
+	sev = psp_master->sev_data;
+
+	if (!sev->snp_inited)
+		return -EINVAL;
+
+	/*
+	 * Check if we have enough space to copy the certificate chain. Otherwise
+	 * return ERROR code defined in the GHCB specification.
+	 */
+	expected_npages = sev->snp_certs_len >> PAGE_SHIFT;
+	if (*npages < expected_npages) {
+		*npages = expected_npages;
+		*fw_err = SNP_GUEST_REQ_INVALID_LEN;
+		return -EINVAL;
+	}
+
+	rc = sev_do_cmd(SEV_CMD_SNP_GUEST_REQUEST, data, (int *)&fw_err);
+	if (rc)
+		return rc;
+
+	/* Copy the certificate blob */
+	if (sev->snp_certs_data) {
+		*npages = expected_npages;
+		memcpy((void *)vaddr, sev->snp_certs_data, *npages << PAGE_SHIFT);
+	} else {
+		*npages = 0;
+	}
+
+	return rc;
+}
+EXPORT_SYMBOL_GPL(snp_guest_ext_guest_request);
+
 static void sev_exit(struct kref *ref)
 {
 	misc_deregister(&misc_dev->misc);
diff --git a/include/linux/psp-sev.h b/include/linux/psp-sev.h
index b72a74f6a4e9..2345ac6ae431 100644
--- a/include/linux/psp-sev.h
+++ b/include/linux/psp-sev.h
@@ -925,6 +925,23 @@ void *psp_copy_user_blob(u64 uaddr, u32 len);
 void *snp_alloc_firmware_page(gfp_t mask);
 void snp_free_firmware_page(void *addr);
 
+/**
+ * snp_guest_ext_guest_request - perform the SNP extended guest request command
+ *  defined in the GHCB specification.
+ *
+ * @data: the input guest request structure
+ * @vaddr: address where the certificate blob need to be copied.
+ * @npages: number of pages for the certificate blob.
+ *    If the specified page count is less than the certificate blob size, then the
+ *    required page count is returned with error code defined in the GHCB spec.
+ *    If the specified page count is more than the certificate blob size, then
+ *    page count is updated to reflect the amount of valid data copied in the
+ *    vaddr.
+ */
+int snp_guest_ext_guest_request(struct sev_data_snp_guest_request *data,
+				unsigned long vaddr, unsigned long *npages,
+				unsigned long *error);
+
 #else	/* !CONFIG_CRYPTO_DEV_SP_PSP */
 
 static inline int
@@ -972,6 +989,13 @@ static inline void *snp_alloc_firmware_page(gfp_t mask)
 
 static inline void snp_free_firmware_page(void *addr) { }
 
+static inline int snp_guest_ext_guest_request(struct sev_data_snp_guest_request *data,
+					      unsigned long vaddr, unsigned long *n,
+					      unsigned long *error)
+{
+	return -ENODEV;
+}
+
 #endif	/* CONFIG_CRYPTO_DEV_SP_PSP */
 
 #endif	/* __PSP_SEV_H__ */
-- 
2.17.1