[PATCH v3 04/10] x86/sev: Cache AP Jump Table Address

From: Joerg Roedel <joro@8bytes.org>
To: x86@kernel.org
Cc: Joerg Roedel <joro@8bytes.org>, Joerg Roedel <jroedel@suse.de>,
	Eric Biederman <ebiederm@xmission.com>,
	kexec@lists.infradead.org, hpa@zytor.com,
	Andy Lutomirski <luto@kernel.org>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Jiri Slaby <jslaby@suse.cz>,
	Dan Williams <dan.j.williams@intel.com>,
	Tom Lendacky <thomas.lendacky@amd.com>,
	Juergen Gross <jgross@suse.com>,
	Kees Cook <keescook@chromium.org>,
	David Rientjes <rientjes@google.com>,
	Cfir Cohen <cfir@google.com>, Erdem Aktas <erdemaktas@google.com>,
	Masami Hiramatsu <mhiramat@kernel.org>,
	Mike Stunes <mstunes@vmware.com>,
	Sean Christopherson <seanjc@google.com>,
	Martin Radev <martin.b.radev@gmail.com>,
	Arvind Sankar <nivedita@alum.mit.edu>,
	linux-coco@lists.linux.dev, linux-kernel@vger.kernel.org,
	kvm@vger.kernel.org, virtualization@lists.linux-foundation.org
Subject: [PATCH v3 04/10] x86/sev: Cache AP Jump Table Address
Date: Thu, 27 Jan 2022 11:10:38 +0100	[thread overview]
Message-ID: <20220127101044.13803-5-joro@8bytes.org> (raw)
In-Reply-To: <20220127101044.13803-1-joro@8bytes.org>

From: Joerg Roedel <jroedel@suse.de>

Store the physical address of the AP jump table in kernel memory so
that it does not need to be fetched from the Hypervisor again.

Signed-off-by: Joerg Roedel <jroedel@suse.de>
---
 arch/x86/kernel/sev.c | 28 +++++++++++++++-------------
 1 file changed, 15 insertions(+), 13 deletions(-)

diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c
index 8a4317fa699a..969ef9855bb5 100644
--- a/arch/x86/kernel/sev.c
+++ b/arch/x86/kernel/sev.c
@@ -43,6 +43,9 @@ static struct ghcb boot_ghcb_page __bss_decrypted __aligned(PAGE_SIZE);
  */
 static struct ghcb __initdata *boot_ghcb;
 
+/* Cached AP jump table Address */
+static phys_addr_t jump_table_pa;
+
 /* #VC handler runtime per-CPU data */
 struct sev_es_runtime_data {
 	struct ghcb ghcb_page;
@@ -523,12 +526,14 @@ void noinstr __sev_es_nmi_complete(void)
 	__sev_put_ghcb(&state);
 }
 
-static u64 get_jump_table_addr(void)
+static phys_addr_t get_jump_table_addr(void)
 {
 	struct ghcb_state state;
 	unsigned long flags;
 	struct ghcb *ghcb;
-	u64 ret = 0;
+
+	if (jump_table_pa)
+		return jump_table_pa;
 
 	local_irq_save(flags);
 
@@ -544,39 +549,36 @@ static u64 get_jump_table_addr(void)
 
 	if (ghcb_sw_exit_info_1_is_valid(ghcb) &&
 	    ghcb_sw_exit_info_2_is_valid(ghcb))
-		ret = ghcb->save.sw_exit_info_2;
+		jump_table_pa = (phys_addr_t)ghcb->save.sw_exit_info_2;
 
 	__sev_put_ghcb(&state);
 
 	local_irq_restore(flags);
 
-	return ret;
+	return jump_table_pa;
 }
 
 int sev_es_setup_ap_jump_table(struct real_mode_header *rmh)
 {
 	u16 startup_cs, startup_ip;
-	phys_addr_t jump_table_pa;
-	u64 jump_table_addr;
 	u16 __iomem *jump_table;
+	phys_addr_t pa;
 
-	jump_table_addr = get_jump_table_addr();
+	pa = get_jump_table_addr();
 
 	/* On UP guests there is no jump table so this is not a failure */
-	if (!jump_table_addr)
+	if (!pa)
 		return 0;
 
-	/* Check if AP Jump Table is page-aligned */
-	if (jump_table_addr & ~PAGE_MASK)
+	/* Check if AP jump table is page-aligned */
+	if (pa & ~PAGE_MASK)
 		return -EINVAL;
 
-	jump_table_pa = jump_table_addr & PAGE_MASK;
-
 	startup_cs = (u16)(rmh->trampoline_start >> 4);
 	startup_ip = (u16)(rmh->sev_es_trampoline_start -
 			   rmh->trampoline_start);
 
-	jump_table = ioremap_encrypted(jump_table_pa, PAGE_SIZE);
+	jump_table = ioremap_encrypted(pa, PAGE_SIZE);
 	if (!jump_table)
 		return -EIO;
 
-- 
2.34.1

