[PATCH 3/6] x86/sev-es: Use __put_user()/__get_user
From: Joerg Roedel <joro@8bytes.org>
Date: 2021-05-12 07:55:25
Also in:
kvm, lkml, stable, virtualization
Subsystem:
the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen
From: Joerg Roedel <redacted>
The put_user() and get_user() functions do checks on the address which is
passed to them. They check whether the address is actually a user-space
address and whether its fine to access it. They also call might_fault()
to indicate that they could fault and possibly sleep.
All of these checks are neither wanted nor required in the #VC exception
handler, which can be invoked from almost any context and also for MMIO
instructions from kernel space on kernel memory. All the #VC handler
wants to know is whether a fault happened when the access was tried.
This is provided by __put_user()/__get_user(), which just do the access
no matter what.
Fixes: f980f9c31a92 ("x86/sev-es: Compile early handler code into kernel image")
Cc: stable@vger.kernel.org # v5.10+
Signed-off-by: Joerg Roedel <redacted>
---
arch/x86/kernel/sev.c | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)
diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c
index 6530a844eb61..110b39345b40 100644
--- a/arch/x86/kernel/sev.c
+++ b/arch/x86/kernel/sev.c@@ -342,22 +342,22 @@ static enum es_result vc_write_mem(struct es_em_ctxt *ctxt, switch (size) { case 1: memcpy(&d1, buf, 1); - if (put_user(d1, target)) + if (__put_user(d1, target)) goto fault; break; case 2: memcpy(&d2, buf, 2); - if (put_user(d2, target)) + if (__put_user(d2, target)) goto fault; break; case 4: memcpy(&d4, buf, 4); - if (put_user(d4, target)) + if (__put_user(d4, target)) goto fault; break; case 8: memcpy(&d8, buf, 8); - if (put_user(d8, target)) + if (__put_user(d8, target)) goto fault; break; default:
@@ -396,22 +396,22 @@ static enum es_result vc_read_mem(struct es_em_ctxt *ctxt, switch (size) { case 1: - if (get_user(d1, s)) + if (__get_user(d1, s)) goto fault; memcpy(buf, &d1, 1); break; case 2: - if (get_user(d2, s)) + if (__get_user(d2, s)) goto fault; memcpy(buf, &d2, 2); break; case 4: - if (get_user(d4, s)) + if (__get_user(d4, s)) goto fault; memcpy(buf, &d4, 4); break; case 8: - if (get_user(d8, s)) + if (__get_user(d8, s)) goto fault; memcpy(buf, &d8, 8); break;
--
2.31.1