linux-kernel - [PATCH 3/3] x86/platform/UV: use efi_runtime

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Message-Id: <20190109104541.25733-4-hedi.berriche@hpe.com>
Date:   Wed,  9 Jan 2019 10:45:41 +0000
From:   Hedi Berriche <hedi.berriche@....com>
To:     Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>
Cc:     x86@...nel.org, linux-efi@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Hedi Berriche <hedi.berriche@....com>,
        Russ Anderson <rja@....com>, Mike Travis <mike.travis@....com>,
        Dimitri Sivanich <sivanich@....com>,
        Steve Wahl <steve.wahl@....com>
Subject: [PATCH 3/3] x86/platform/UV: use efi_runtime_sem to serialise BIOS calls

Calls into UV firmware must be protected against concurrency, use the
now visible efi_runtime_sem lock to serialise them.

Signed-off-by: Hedi Berriche <hedi.berriche@....com>
Reviewed-by: Russ Anderson <rja@....com>
Reviewed-by: Mike Travis <mike.travis@....com>
Reviewed-by: Dimitri Sivanich <sivanich@....com>
Reviewed-by: Steve Wahl <steve.wahl@....com>
---
 arch/x86/include/asm/uv/bios.h |  3 ++-
 arch/x86/platform/uv/bios_uv.c | 25 ++++++++++++++++++++++---
 2 files changed, 24 insertions(+), 4 deletions(-)

diff --git a/arch/x86/include/asm/uv/bios.h b/arch/x86/include/asm/uv/bios.h
index 4eee646544b2..33e94aa0b1ff 100644
--- a/arch/x86/include/asm/uv/bios.h
+++ b/arch/x86/include/asm/uv/bios.h
@@ -48,7 +48,8 @@ enum {
 	BIOS_STATUS_SUCCESS		=  0,
 	BIOS_STATUS_UNIMPLEMENTED	= -ENOSYS,
 	BIOS_STATUS_EINVAL		= -EINVAL,
-	BIOS_STATUS_UNAVAIL		= -EBUSY
+	BIOS_STATUS_UNAVAIL		= -EBUSY,
+	BIOS_STATUS_ABORT		= -EINTR
 };
 
 /* Address map parameters */
diff --git a/arch/x86/platform/uv/bios_uv.c b/arch/x86/platform/uv/bios_uv.c
index cd05af157763..92f960798e20 100644
--- a/arch/x86/platform/uv/bios_uv.c
+++ b/arch/x86/platform/uv/bios_uv.c
@@ -29,7 +29,8 @@
 
 struct uv_systab *uv_systab;
 
-s64 uv_bios_call(enum uv_bios_cmd which, u64 a1, u64 a2, u64 a3, u64 a4, u64 a5)
+s64 __uv_bios_call(enum uv_bios_cmd which, u64 a1, u64 a2, u64 a3,
+			u64 a4, u64 a5)
 {
 	struct uv_systab *tab = uv_systab;
 	s64 ret;
@@ -44,13 +45,26 @@ s64 uv_bios_call(enum uv_bios_cmd which, u64 a1, u64 a2, u64 a3, u64 a4, u64 a5)
 	 * If EFI_OLD_MEMMAP is set, we need to fall back to using our old EFI
 	 * callback method, which uses efi_call() directly, with the kernel page tables:
 	 */
-	if (unlikely(test_bit(EFI_OLD_MEMMAP, &efi.flags)))
+	if (unlikely(efi_enabled(EFI_OLD_MEMMAP)))
 		ret = efi_call((void *)__va(tab->function), (u64)which, a1, a2, a3, a4, a5);
 	else
 		ret = efi_call_virt_pointer(tab, function, (u64)which, a1, a2, a3, a4, a5);
 
 	return ret;
 }
+
+s64 uv_bios_call(enum uv_bios_cmd which, u64 a1, u64 a2, u64 a3, u64 a4, u64 a5)
+{
+	s64 ret;
+
+	if (down_interruptible(&efi_runtime_sem))
+		return BIOS_STATUS_ABORT;
+
+	ret = __uv_bios_call(which, a1, a2, a3, a4, a5);
+	up(&efi_runtime_sem);
+
+	return ret;
+}
 EXPORT_SYMBOL_GPL(uv_bios_call);
 
 s64 uv_bios_call_irqsave(enum uv_bios_cmd which, u64 a1, u64 a2, u64 a3,
@@ -59,10 +73,15 @@ s64 uv_bios_call_irqsave(enum uv_bios_cmd which, u64 a1, u64 a2, u64 a3,
 	unsigned long bios_flags;
 	s64 ret;
 
+	if (down_interruptible(&efi_runtime_sem))
+		return BIOS_STATUS_ABORT;
+
 	local_irq_save(bios_flags);
-	ret = uv_bios_call(which, a1, a2, a3, a4, a5);
+	ret = __uv_bios_call(which, a1, a2, a3, a4, a5);
 	local_irq_restore(bios_flags);
 
+	up(&efi_runtime_sem);
+
 	return ret;
 }
 
-- 
2.20.0