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From: Tianyu Lan <ltykernel@gmail.com>
To: kys@microsoft.com, haiyangz@microsoft.com, wei.liu@kernel.org,
	decui@microsoft.com, tglx@linutronix.de, mingo@redhat.com,
	bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org,
	hpa@zytor.com, daniel.lezcano@linaro.org, arnd@arndb.de,
	michael.h.kelley@microsoft.com
Cc: Tianyu Lan <tiala@microsoft.com>,
	linux-arch@vger.kernel.org, linux-hyperv@vger.kernel.org,
	linux-kernel@vger.kernel.org, vkuznets@redhat.com
Subject: [PATCH V2 4/9] drivers: hv: Mark percpu hvcall input arg page unencrypted in SEV-SNP enlightened guest
Date: Mon, 26 Jun 2023 23:22:42 -0400	[thread overview]
Message-ID: <20230627032248.2170007-5-ltykernel@gmail.com> (raw)
In-Reply-To: <20230627032248.2170007-1-ltykernel@gmail.com>

From: Tianyu Lan <tiala@microsoft.com>

Hypervisor needs to access input arg, VMBus synic event and
message pages. Mark these pages unencrypted in the SEV-SNP
guest and free them only if they have been marked encrypted
successfully.

Signed-off-by: Tianyu Lan <tiala@microsoft.com>
---
 drivers/hv/hv.c        | 57 +++++++++++++++++++++++++++++++++++++++---
 drivers/hv/hv_common.c | 13 ++++++++++
 2 files changed, 67 insertions(+), 3 deletions(-)

diff --git a/drivers/hv/hv.c b/drivers/hv/hv.c
index de6708dbe0df..ec6e35a0d9bf 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 */
@@ -78,7 +79,7 @@ int hv_post_message(union hv_connection_id connection_id,
 
 int hv_synic_alloc(void)
 {
-	int cpu;
+	int cpu, ret = -ENOMEM;
 	struct hv_per_cpu_context *hv_cpu;
 
 	/*
@@ -123,26 +124,76 @@ int hv_synic_alloc(void)
 				goto err;
 			}
 		}
+
+		if (hv_isolation_type_en_snp()) {
+			ret = set_memory_decrypted((unsigned long)
+				hv_cpu->synic_message_page, 1);
+			if (ret) {
+				pr_err("Failed to decrypt SYNIC msg page: %d\n", ret);
+				hv_cpu->synic_message_page = NULL;
+
+				/*
+				 * Free the event page here so that hv_synic_free()
+				 * won't later try to re-encrypt it.
+				 */
+				free_page((unsigned long)hv_cpu->synic_event_page);
+				hv_cpu->synic_event_page = NULL;
+				goto err;
+			}
+
+			ret = set_memory_decrypted((unsigned long)
+				hv_cpu->synic_event_page, 1);
+			if (ret) {
+				pr_err("Failed to decrypt SYNIC event page: %d\n", ret);
+				hv_cpu->synic_event_page = NULL;
+				goto err;
+			}
+
+			memset(hv_cpu->synic_message_page, 0, PAGE_SIZE);
+			memset(hv_cpu->synic_event_page, 0, PAGE_SIZE);
+		}
 	}
 
 	return 0;
+
 err:
 	/*
 	 * Any memory allocations that succeeded will be freed when
 	 * the caller cleans up by calling hv_synic_free()
 	 */
-	return -ENOMEM;
+	return ret;
 }
 
 
 void hv_synic_free(void)
 {
-	int cpu;
+	int cpu, ret;
 
 	for_each_present_cpu(cpu) {
 		struct hv_per_cpu_context *hv_cpu
 			= per_cpu_ptr(hv_context.cpu_context, cpu);
 
+		/* It's better to leak the page if the encryption fails. */
+		if (hv_isolation_type_en_snp()) {
+			if (hv_cpu->synic_message_page) {
+				ret = set_memory_encrypted((unsigned long)
+					hv_cpu->synic_message_page, 1);
+				if (ret) {
+					pr_err("Failed to encrypt SYNIC msg page: %d\n", ret);
+					hv_cpu->synic_message_page = NULL;
+				}
+			}
+
+			if (hv_cpu->synic_event_page) {
+				ret = set_memory_encrypted((unsigned long)
+					hv_cpu->synic_event_page, 1);
+				if (ret) {
+					pr_err("Failed to encrypt SYNIC event page: %d\n", ret);
+					hv_cpu->synic_event_page = NULL;
+				}
+			}
+		}
+
 		free_page((unsigned long)hv_cpu->synic_event_page);
 		free_page((unsigned long)hv_cpu->synic_message_page);
 	}
diff --git a/drivers/hv/hv_common.c b/drivers/hv/hv_common.c
index 4b4aa53c34c2..2d43ba2bc925 100644
--- a/drivers/hv/hv_common.c
+++ b/drivers/hv/hv_common.c
@@ -24,6 +24,7 @@
 #include <linux/kmsg_dump.h>
 #include <linux/slab.h>
 #include <linux/dma-map-ops.h>
+#include <linux/set_memory.h>
 #include <asm/hyperv-tlfs.h>
 #include <asm/mshyperv.h>
 
@@ -359,6 +360,7 @@ int hv_common_cpu_init(unsigned int cpu)
 	u64 msr_vp_index;
 	gfp_t flags;
 	int pgcount = hv_root_partition ? 2 : 1;
+	int ret;
 
 	/* hv_cpu_init() can be called with IRQs disabled from hv_resume() */
 	flags = irqs_disabled() ? GFP_ATOMIC : GFP_KERNEL;
@@ -378,6 +380,17 @@ int hv_common_cpu_init(unsigned int cpu)
 			outputarg = (void **)this_cpu_ptr(hyperv_pcpu_output_arg);
 			*outputarg = (char *)(*inputarg) + HV_HYP_PAGE_SIZE;
 		}
+
+		if (hv_isolation_type_en_snp()) {
+			ret = set_memory_decrypted((unsigned long)*inputarg, pgcount);
+			if (ret) {
+				kfree(*inputarg);
+				*inputarg = NULL;
+				return ret;
+			}
+
+			memset(*inputarg, 0x00, pgcount * PAGE_SIZE);
+		}
 	}
 
 	msr_vp_index = hv_get_register(HV_REGISTER_VP_INDEX);
-- 
2.25.1


  parent reply	other threads:[~2023-06-27  3:28 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-06-27  3:22 [PATCH V2 0/9] x86/hyperv: Add AMD sev-snp enlightened guest support on hyperv Tianyu Lan
2023-06-27  3:22 ` [PATCH V2 1/9] x86/hyperv: Add sev-snp enlightened guest static key Tianyu Lan
2023-07-04 14:17   ` Michael Kelley (LINUX)
2023-07-05 14:43     ` Tianyu Lan
2023-06-27  3:22 ` [PATCH V2 2/9] x86/hyperv: Set Virtual Trust Level in VMBus init message Tianyu Lan
2023-07-04 14:18   ` Michael Kelley (LINUX)
2023-07-07  9:07   ` [EXTERNAL] " Saurabh Singh Sengar
2023-08-07  4:48     ` Wei Liu
2023-08-10 16:22       ` Tianyu Lan
2023-08-11  2:55         ` Saurabh Singh Sengar
2023-06-27  3:22 ` [PATCH V2 3/9] x86/hyperv: Mark Hyper-V vp assist page unencrypted in SEV-SNP enlightened guest Tianyu Lan
2023-07-04 14:18   ` Michael Kelley (LINUX)
2023-06-27  3:22 ` Tianyu Lan [this message]
2023-07-04 14:19   ` [PATCH V2 4/9] drivers: hv: Mark percpu hvcall input arg " Michael Kelley (LINUX)
2023-06-27  3:22 ` [PATCH V2 5/9] x86/hyperv: Use vmmcall to implement Hyper-V hypercall in sev-snp " Tianyu Lan
2023-06-27  3:22 ` [PATCH V2 6/9] clocksource: hyper-v: Mark hyperv tsc page unencrypted " Tianyu Lan
2023-07-04 14:19   ` Michael Kelley (LINUX)
2023-06-27  3:22 ` [PATCH V2 7/9] x86/hyperv: Initialize cpu and memory for SEV-SNP " Tianyu Lan
2023-07-04 14:23   ` Michael Kelley (LINUX)
2023-06-27  3:22 ` [PATCH V2 8/9] x86/hyperv: Add smp support for SEV-SNP guest Tianyu Lan
2023-07-04 14:24   ` Michael Kelley (LINUX)
2023-06-27  3:22 ` [PATCH V2 9/9] x86/hyperv: Add hyperv-specific handling for VMMCALL under SEV-ES Tianyu Lan
2023-07-04 14:25   ` Michael Kelley (LINUX)

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