linux-kernel - [RFC PATCH V2 08/18] x86/hyperv: decrypt vmbus pages for sev-snp enlightened guest

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Date:   Fri, 18 Nov 2022 22:46:22 -0500
From:   Tianyu Lan <ltykernel@...il.com>
To:     luto@...nel.org, tglx@...utronix.de, mingo@...hat.com,
        bp@...en8.de, dave.hansen@...ux.intel.com, x86@...nel.org,
        hpa@...or.com, seanjc@...gle.com, pbonzini@...hat.com,
        jgross@...e.com, tiala@...rosoft.com, kirill@...temov.name,
        jiangshan.ljs@...group.com, peterz@...radead.org,
        ashish.kalra@....com, srutherford@...gle.com,
        akpm@...ux-foundation.org, anshuman.khandual@....com,
        pawan.kumar.gupta@...ux.intel.com, adrian.hunter@...el.com,
        daniel.sneddon@...ux.intel.com, alexander.shishkin@...ux.intel.com,
        sandipan.das@....com, ray.huang@....com, brijesh.singh@....com,
        michael.roth@....com, thomas.lendacky@....com,
        venu.busireddy@...cle.com, sterritt@...gle.com,
        tony.luck@...el.com, samitolvanen@...gle.com, fenghua.yu@...el.com
Cc:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        linux-hyperv@...r.kernel.org, linux-arch@...r.kernel.org
Subject: [RFC PATCH V2 08/18] x86/hyperv: decrypt vmbus pages for sev-snp enlightened guest

From: Tianyu Lan <tiala@...rosoft.com>

Vmbus int, synic and post message pages are shared with hypervisor
and so decrypt these pages in the sev-snp guest.

Signed-off-by: Tianyu Lan <tiala@...rosoft.com>
---
 drivers/hv/connection.c | 13 +++++++++++++
 drivers/hv/hv.c         | 32 +++++++++++++++++++++++++++++++-
 2 files changed, 44 insertions(+), 1 deletion(-)

diff --git a/drivers/hv/connection.c b/drivers/hv/connection.c
index 9dc27e5d367a..43141225ea15 100644
--- a/drivers/hv/connection.c
+++ b/drivers/hv/connection.c
@@ -215,6 +215,15 @@ int vmbus_connect(void)
 		(void *)((unsigned long)vmbus_connection.int_page +
 			(HV_HYP_PAGE_SIZE >> 1));
 
+	if (hv_isolation_type_snp() || hv_isolation_type_en_snp()) {
+		ret = set_memory_decrypted((unsigned long)
+				vmbus_connection.int_page, 1);
+		if (ret)
+			goto cleanup;
+
+		memset(vmbus_connection.int_page, 0, PAGE_SIZE);
+	}
+
 	/*
 	 * Setup the monitor notification facility. The 1st page for
 	 * parent->child and the 2nd page for child->parent
@@ -372,6 +381,10 @@ void vmbus_disconnect(void)
 		destroy_workqueue(vmbus_connection.work_queue);
 
 	if (vmbus_connection.int_page) {
+		if (hv_isolation_type_en_snp())
+			set_memory_encrypted((unsigned long)
+				vmbus_connection.int_page, 1);
+
 		hv_free_hyperv_page((unsigned long)vmbus_connection.int_page);
 		vmbus_connection.int_page = NULL;
 	}
diff --git a/drivers/hv/hv.c b/drivers/hv/hv.c
index 4d6480d57546..f9111eb32739 100644
--- a/drivers/hv/hv.c
+++ b/drivers/hv/hv.c
@@ -20,6 +20,7 @@
 #include <linux/interrupt.h>
 #include <clocksource/hyperv_timer.h>
 #include <asm/mshyperv.h>
+#include <linux/set_memory.h>
 #include "hyperv_vmbus.h"
 
 /* The one and only */
@@ -117,7 +118,7 @@ int hv_post_message(union hv_connection_id connection_id,
 
 int hv_synic_alloc(void)
 {
-	int cpu;
+	int cpu, ret;
 	struct hv_per_cpu_context *hv_cpu;
 
 	/*
@@ -168,6 +169,29 @@ int hv_synic_alloc(void)
 			pr_err("Unable to allocate post msg page\n");
 			goto err;
 		}
+
+		if (hv_isolation_type_en_snp()) {
+			ret = set_memory_decrypted((unsigned long)
+				hv_cpu->synic_message_page, 1);
+			ret |= set_memory_decrypted((unsigned long)
+				hv_cpu->synic_event_page, 1);
+			ret |= set_memory_decrypted((unsigned long)
+				hv_cpu->post_msg_page, 1);
+
+			if (ret) {
+				set_memory_encrypted((unsigned long)
+					hv_cpu->synic_message_page, 1);
+				set_memory_encrypted((unsigned long)
+					hv_cpu->synic_event_page, 1);
+				set_memory_encrypted((unsigned long)
+					hv_cpu->post_msg_page, 1);
+				goto err;
+			}
+
+			memset(hv_cpu->synic_message_page, 0, PAGE_SIZE);
+			memset(hv_cpu->synic_event_page, 0, PAGE_SIZE);
+			memset(hv_cpu->post_msg_page, 0, PAGE_SIZE);
+		}
 	}
 
 	return 0;
@@ -188,6 +212,12 @@ void hv_synic_free(void)
 		struct hv_per_cpu_context *hv_cpu
 			= per_cpu_ptr(hv_context.cpu_context, cpu);
 
+		if (hv_isolation_type_en_snp()) {
+			set_memory_encrypted((unsigned long)hv_cpu->synic_message_page, 1);
+			set_memory_encrypted((unsigned long)hv_cpu->synic_event_page, 1);
+			set_memory_encrypted((unsigned long)hv_cpu->post_msg_page, 1);
+		}
+
 		free_page((unsigned long)hv_cpu->synic_event_page);
 		free_page((unsigned long)hv_cpu->synic_message_page);
 		free_page((unsigned long)hv_cpu->post_msg_page);
-- 
2.25.1