Blame 0241-pseries-Don-t-test-for-MSR_PR-for-hypercalls-under-K.patch

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From 45af32e160bf339974a74bb8a38384b95aa2f555 Mon Sep 17 00:00:00 2001
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From: David Gibson <david@gibson.dropbear.id.au>
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Date: Tue, 25 Sep 2012 17:12:20 +0000
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Subject: [PATCH] pseries: Don't test for MSR_PR for hypercalls under KVM
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PAPR hypercalls should only be invoked from the guest kernel, not guest
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user programs, that is, with MSR[PR]=0.  Currently we check this in
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spapr_hypercall, returning H_PRIVILEGE if MSR[PR]=1.
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However, under KVM the state of MSR[PR] is already checked by the host
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kernel before passing the hypercall to qemu, making this check redundant.
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Worse, however, we don't generally synchronize KVM and qemu state on the
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hypercall path, meaning that qemu could incorrectly reject a hypercall
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because it has a stale MSR value.
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This patch fixes the problem by moving the privilege test exclusively to
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the TCG hypercall path.
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Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
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CC: qemu-stable@nongnu.org
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Signed-off-by: Alexander Graf <agraf@suse.de>
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(cherry picked from commit efcb9383b974114e5f682e531346006f8f2466c0)
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Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
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---
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 hw/spapr.c       | 7 ++++++-
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 hw/spapr_hcall.c | 5 -----
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 2 files changed, 6 insertions(+), 6 deletions(-)
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diff --git a/hw/spapr.c b/hw/spapr.c
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index c34b767..5e55430 100644
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--- a/hw/spapr.c
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+++ b/hw/spapr.c
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@@ -556,7 +556,12 @@ static uint64_t translate_kernel_address(void *opaque, uint64_t addr)
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 static void emulate_spapr_hypercall(CPUPPCState *env)
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 {
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-    env->gpr[3] = spapr_hypercall(env, env->gpr[3], &env->gpr[4]);
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+    if (msr_pr) {
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+        hcall_dprintf("Hypercall made with MSR[PR]=1\n");
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+        env->gpr[3] = H_PRIVILEGE;
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+    } else {
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+        env->gpr[3] = spapr_hypercall(env, env->gpr[3], &env->gpr[4]);
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+    }
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 }
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 static void spapr_reset(void *opaque)
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diff --git a/hw/spapr_hcall.c b/hw/spapr_hcall.c
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index abd847f..38098f7 100644
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--- a/hw/spapr_hcall.c
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+++ b/hw/spapr_hcall.c
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@@ -713,11 +713,6 @@ void spapr_register_hypercall(target_ulong opcode, spapr_hcall_fn fn)
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 target_ulong spapr_hypercall(CPUPPCState *env, target_ulong opcode,
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                              target_ulong *args)
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 {
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-    if (msr_pr) {
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-        hcall_dprintf("Hypercall made with MSR[PR]=1\n");
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-        return H_PRIVILEGE;
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-    }
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-
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     if ((opcode <= MAX_HCALL_OPCODE)
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         && ((opcode & 0x3) == 0)) {
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         spapr_hcall_fn fn = papr_hypercall_table[opcode / 4];
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-- 
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1.7.12.1
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